There are not many differences in these Spyders. If you are just getting started and the Rodeo comes with a mask, tank and hopper it would be a good deal. If not you should look for New '07 Sonix or better yet an Xtra. Both of these are in that price range with the Sonix at $110 and the Xtra at $130. Both have top cocking delrin bolts and are actual new guns and not year old guns for new gun prices like a Discontinued Rodeo for $100. Good things about the Rodeo is it has a regulator. Thats about it for what I can think of.
the imagine has an elactronic frame, making the trigger pull VEY light and giving it the ability to shot faster as a result. Penz is right about all spyders being the same on the inside; except the electronic frame is a vast improvment over the mechanical frame if you're looking for extra speed.
I gots an Imagine, and it's amazing!!! with all the mods from www.OtterSCCustoms.com and a few of my own, it shoots like a champ!
They are cheap too, and you shouldn't have too much of a problem with them. Spyders are great beginer guns, and nice project guns too for home made modifications :P
I have two Spyders with E-frames, an AMG LCD and an E-99 Avant that is half backed. My AMG runs at 280psi and is great except the 13 BPS limit but that is still fast enough. The E-99 tops out at 14BPS and is modded to be a switchable reactive trigger. If you start with a Spyder you can mod it to be low pressure and electronic or just give it a custom look. I have been using Spyders since '97 and still love them.