Yep if you'll already have a herpstat available there's not much else you'll need....I'm just throwing a wild guess of about $30 or less and you'll have a running bator.
There's plenty of threads with instructions for making your own here and elsewhere on the internet....even videos on youtube.
But that pro 148 would be a better buy for only $15 more...looks much more solid. Should help with any humidity problems mentioned in earlier posts about the reptibator.
Sorry I'm talking so much, I don't have either one of these....just giving my 2 cents. (bored at work)
Forgot to bring shipping costs into the mix! That pro148 is overweight....