I just got one on trade this past Sunday. I know where you can get one for $450, like new, as the guy had a few of them. You'll pay shipping but still, thats a good price IMO. I'm a lefty as well. Most of my shotguns are doubles or mossbergs due to the top tang safety. I know that there are LH models of popular shotguns out there but theyre never readily available and often as such command a higher price. After shooting doubles most of my life I've become accustomed to a top tang.
About the BPS....I hunted with a buddy who used one and he let me use it one day out goose hunting and I had wanted one ever since. I like the weight of it, it absorbs recoil better and has a more fluid swing to it that I like. I like the bottom feed/eject, its truly ambidextrous. Browning is synonymous with quality. Nice wood and deep rich blueing is the norm. Invector chokes are very reasonably priced and available. If you keep it in nice shape you won't lose value in it, used brownings in good shape hold their value pretty well. I don't think the BPS has a rival as far as pump guns go. Maybe a nice older wingmaster, but thats it.
The action is notoriously maintenance free, maybe some compressed air in the action time to time, wipe it down and put a drop of oil on the action bars, that's it. Most people report more wear and tear from over cleaning and disassembly/reassembly than actual shooting/use.
I got mine for a trade but the guy was asking $450, it has beautiful high gloss walnut and nice blueing, with game scenes engraved on both sides of the receiver. He said he had its twin and additionally a more plainly stated model as well for sale.