I believe the cen genesis has a conversion of some sort available? truck itself is 5 or 600, atleast a few more hundred to get it running gas.

the 1/5th and 1/6th scale trucks all run gas, but those are way above that price range.

gas engines in that scale just dont really exist. not sure if they cant exist for engineering reasons, or just arent worthwhile. some have use 4stroke nitro engines in trucks with some interesting results, but even that is still talking heavy modification with a high cost.