A quick check of past eBay items shows them selling for anywhere between $400ish and $600 or $700. Looks like more money with the acrylic case. Price on this seems fair though as you said it's not over yet.
General eBay (and collectibles in general) rule for me is, an item is only worth what I'm willing to pay for it. I don't care if I can buy something I kinda like for a great price and sell it for a lot more. I look for what I want and go after it, within reason. My advice, if you're keen to bid: figure out what the highest price you'd be willing to spend is. Then enter that as your max bid with about 20 or 30 seconds to go in the auction. Keeps you from overbidding due to spur of the moment decision making, and keeps other bidders from prodding away at your max bid with their own guesses at what they think they might want to pay. I don't like giving them the time to do so. If you win, you win. If you're outbid, you move on to look for it at the price you're willing to pay, knowing someone else just wanted to spend more (or was foolishly impulse bidding).
Good luck! Post pics here if you do win it.