After doing some more digging, I think I'm going to go with the Cyberpower 1500VA
model. The company is apparently in the process of setting up a system where you can buy replacement batteries directly from them. I'm thinking they'd have it running by the time replacement would be necessary. If not, they actually do provide part numbers so you can buy them on your own. I like the aesthetics of the Cyberpower unit, and it seems to have received more consistent positive reviews than the comparable APC. It can also be had for about $170-175 shipped from some places, which undercuts Newegg by a bit.