From what I gather, and it's limited, Pop really likes the spacing Bonner provides and is not likely to depart from him unless another floor stretcher is unearthed. Haislip has an opportunity, but Bonner has outperformed him in every way thus far. The Spurs won't trade him unless a) the talent coming back is too good to pass up and/or b) they have a replacement player with a similar skill set (Haislip?).
Joe Alexander would be interesting as a D-League trial run, but I don't see a deal that works. It's hard to imagine the Spurs moving an important piece like Finley just to get a look at Joe Alexander.