No, under no circumstances mix species! (One reason being that they come from different environments/climates and need different kinds of heat, substrate, moisture, etc. Another reason being that they might hurt, kill, eat each other. Another being that they might transfer parasites to each other... countless other reasons...)
Just buy a 10-gallon tank for like 14 bucks at PETCO (or use an old fish tank). It's so cheap. UTH's are cheap at amazon.com.
thank chrissy. i was thinkiong a buying a panther gecko but im not sure i hav room for another wide 10 gal tank. maybe ill buy a 20gal tall and put a crestie in there. thank again, big help