The iguanid family is a very large group of lizards and there are a few smaller veg eating lizards in that family

chuckwallas, desert iggys etc, on the other hand you could always consider a tortoise?
My advice would be to find one of those lizards that really attract you, research their needs because it isn't a simple case of just feeding "any old veg and some foods are hard to come by and find"" and locate and aquire one, this would be much better for you and probibly the lizard because you have a keen interest in keeping it, rather than just keeping any old veg eating lizard for the hell of it, just because it is a convenience if that makes sense.
P.s I would be feeding a crested gecko an omnivore diet, not simply because they will snatch up the odd insect, but it gives them some enrichment too (hunting, catching etc) but thats just me good luck..:2thumb: