Your S3 can be sold on ebay or craigslist. Just because BB won't offer you anything doesn't mean it's not worth anything.
It sounds to me like you picked the wrong product. If it's lagging at a certain task that you needed, then a more capable processor or more ram should've been a consideration when you purchased. Not purchase the lowest cost model and be disappointed when it doesn't meet your demands.
Windows tablets don't have the luxury of "just works" because there are so many variables and functions it must do outside of just running 1 app or game optimized just for ipads.
You may be right about picking the wrong model although all I really do with it is surf the net and use evernote web. I have a laptop for work and it even folds back yoga-style, to turn into a tablet. It's an HP. Plus I've got my Macbook Air. Though, I think a 128 GB Cherry Trail tablet made by Microsoft themselves with 4 GB of RAM, that costs almost $1000 with accessories should be able to handle web browsing. That said, my plan is to keep it around for now. Even if and when I get the Pro (iPad or Surface) I will want a backup for when it's charging or whatever. It's not really that bad a tablet. I was just a little bit let down from more glitches and bugs than I expected.