I have attached a dump of the monitor, basic, and chargen ROMs below.
As for price, prices on kit type items are hard to nail down, and I don't recall ever seeing any others besides that unassembled one on eBay. That is in decent enough condition I would expect at minimum a couple hundred from eBeh these days. But it very likely could go for much more than that. Some kits can sell for ridiculous prices. Not sure if it would match an unassembled kit, but someone might prefer an assembled one. If you are not in a hurry, just start a high buy it-now and slowly relist working your way down. It seems unique enough that a bid auction might not be too risky. (So my wild-ass-guess would be perhaps $200-$400, but I think you should do more research).
One suggestion, that looks like it might be a bit customized. If you can, it would help to get photos of the guts inside it. A buyer would want to see that all required chips are present, boards are in good condition, and if anything too odd has been added. (also, what is the deal with that red tape on the keyboard? Broken keys?)