TORONTO - Add one more discretionary purchase to the already long list of things that could get more expensive because of high gas prices -- concert tickets.

Industry watchers say concert sales were "remarkably robust" in the first half of the year -- considering the rise in fuel prices and tough economic times in parts of North America -- but artists' tour budgets may now have to be adjusted going forward.

And that could mean even higher ticket prices.

"Most of the tours that were budgeted this summer were budgeted much earlier in the year before the price of fuel went up," said Gary Bongiovanni, editor of industry magazine Pollstar. "I think you'll probably see more of an impact going forward in the second half of the year as people now have a chance to plan what they're going to do for their fall tours."

The prices of tickets for the music world's biggest acts have already shot up in recent years and while fans have been willing to pay, their breaking point may be near, Bongiovanni said.

The highest grossing North American tour in the first half of 2008 was Bon Jovi's which brought in $56.3 million, with an average ticket price of $88 and a total of more than 639,000 tickets sold, according to Pollstar .

Canadian crooner Michael Buble was No. 5 on the list with $32.5 million in gross sales and an average ticket price of $71.

Other Canadian acts that cracked the Top 100 included Rush at No. 12 (average ticket price $66), Three Days Grace touring with Breaking Benjamin at No. 58 (average ticket price $32.50), Anne Murray at No. 73 (average ticket price $55), Blue Rodeo at No. 84 (average ticket price $44) and Leonard Cohen at No. 93 (average ticket price $112).

"Fans have proven they'll pay a pretty significant premium to see artists that they're really big fans of, but the continual rising costs of concert tickets is having an impact on the number of tickets we're selling, even if we're grossing more money," Bongiovanni said.

While a fuel surcharge could easily be hidden within the price of tickets for the biggest concerts, Bongiovanni said it's more likely that productions might be scaled back instead to offset the cost of fuel.

"All the bigger artists whose fuel bills are much greater -- because we're talking about fleets of buses and trucks -- are taking a hard look at their production, and do they really need all those trucks, and all those buses, and all those people on the road or can they do it more economically," he said.

Artists that lug their own gear in a van and play bars anywhere they can are suffering, Bongiovanni said.

"A lot of the younger bands that are essentially just trying to develop a reputation and tour on a subsistence level are having a real hard time with it, simply because they can't break even on the road," he said.

Jeff Cohen, who co-owns Toronto's venerable Horseshoe Tavern and a company that books talent at most of the city's major clubs, said he's been hearing plenty of gripes from indie bands who are "definitely feeling the pinch."

Playing shows at bars has never been about making any real money -- since there's little to be made playing for audiences that may not have heard of you, and may not care about you at all -- but owners aren't likely to be sympathetic enough to increase a band's fee, Cohen said.

Better-known bands playing small clubs might start raising ticket prices by a dollar or two -- which would represent a significant percentage markup on a $10 or $20 ticket -- although everyone's trying to avoid that if possible, Cohen said.

"I do see the gas prices causing a little bit of an increase in ticket pricing, no question, but a small one," he said.

"Because the lower the price, the more chance your band is going to develop, and the higher the price, people will have to think twice about making that investment."

Although the DJ duo known as Team Canada regularly travels the world to spin in clubs and at private parties -- they were invited to play at a birthday bash for Paris Hilton -- DJ Aaron Waisglass said he's in no position to demand gas money and still struggles with the cost of driving to Canadian gigs, and the fuel surcharges that are making flights increasing expensive.

The DJs have spent the past 10 years criss-crossing the country to build up their name, but even with their major successes in recent years -- and serious paydays for big shows -- they still have to budget closely for travel. That sometimes means turning down high-profile gigs simply because it wouldn't be profitable to make the trip, Waisglass said.

"We've said no to shows that a lot of DJs would think we're crazy for turning down the amount of money we got offered, but sometimes but we look at it and it just doesn't make any sense," Waisglass said.

"The problem is we don't tour like a band, we do a lot of one-offs and weekends away, so we might be in Edmonton on Friday, Vancouver on Saturday, Atlantic City on Monday and then back to Montreal. Our tours don't always make sense in terms of the direction we're going, we just kind of have to go where we have to go."

The DJs often book gigs months in advance and don't know where the price of fuel will be in, say, October or November. Since promoters only sometimes pick up travel costs, the duo don't know whether a show will end up being worth their time at all.

Waisglass recently drove about six hours from Montreal to Burlington, Ont., so he could catch a cheaper flight for a show in Baltimore and still make some money out of the gig.

Bongiovanni said artists and tour managers will have to be strategic in their planning in the next year because of the way the industry and gas prices are going, and may want to be conservative in where they play, how elaborate they make their shows and how much they ask fans to pay for tickets.

"When economic times are tough, fans are going to be much quicker to recognize and appreciate a good deal when they see it," he said.

"They will also be faster in getting angry that a show is priced beyond their means."