I found that making the transition into 'seller' on eBay is much easier if you at least have some good buyer feedback. So long as people see that you've been active and are trustworthy, I don't think you'll have any trouble finding some buyers
Same thing with the Arena, once I built up some feedback from buying, no one seemed hesitant to make purchases from me. The only tips I'd give is to be sure you make your potential buyers feel comfortable- describe items extremely well, lots of photos, and adding a return policy doesn't hurt either. Good luck with unloading some of your ponies!