lowestfuel.com
While I like the "gasbuddy" idea, I do hate competing with an established provider. Where this could hit is when gas becomes more of a household topic. In that: Oil hit $56 a barrell this morning, and will continue to go up. Competition will increase among the fuel marketeres, and maybe lead content will come back into question, or a million other quality issues. I like "fuel" somewhat as it is more universal than "gas" or "petrol" (regional), although not ideal. Hold onto this one as you might get lucky that a big gun comes along with a campaign about having the fuel lowest in _____ (something) or similar. If you get lucky on that front, high $x,xxx to mid $xx,xxx potential there. That is, however, a long shot. Better than other markets, however, since gas/fuel/oil is such an expensive market, and the big players have the cash on hand to pay whatever they want for a marketing device (domain name). Wholesale at this point would be mid $xx to low $xxx (say, $50 to $200 or so). For that, I'd personally be content to sit on it and hope for some luck (Better odds than the lottery at least).
samehour.com
Much more general applicability here, but aside from the photography thing or maybe an oil change/mechanic's place, I don't see high priced end users circling this one. Overture is a "0" for "same hour", and google is 145K but the first result is a Bible reference (From Luke). Anyhow, good keywords that match, but not highly popular ATM. End user: $500 - $1,250. Wholesale, $40-$80.
Best of luck,
Allan