The only free vinyl cutting software that I know of right now is Inkcut for Inkskcape.
Other than that one there isn't a free solution out there. Your best bet for the price could be VinylMaster Cut but I have never used it. I would recommend Flexistarter which is a lighter version than Flexi but that isn't free nor a plugin for illustrator. I wouldn't skimp on the software personally but thats just me.
There are some other great ones you might like such as:
Most of the ones I listed you can source used for on Ebay for the dongles that plug into the back of your computer.
If you're pressed to find one for Illustrator the only one I've used and recommend is the one by Onyx. There is Roland Cutstudio plugin for Illustrator but I have never used it but you might consider it. Also, have you checked Roland's site to make sure this isnt any software or drivers that would work??