When buying LED lamps, look at the lumen output not the price.
Lower lumens means less light output.
A standard 4 foot T8 lamp puts out just under 3,000 lumens.
The older T12 lamp is around 2,600 lumens.
Keep that in mind when looking at the 4 foot LED replacement lamps.
If your booth had nice and bright lighting with the fluorescent lamps and you replace them with cheap LED lamps there's a good chance you're going to be disappointed.
EDIT- Some of the LED replacement lamps you can get at the big box stores are for fixtures that still have the fluorescent ballasts in them so be sure to get the lamps that are for fixtures that have been re-wired like yours.