Keep a beady eye out second hand. I've got a Yamaha FG 413S 12 with B-band electronics in that I paid the first owner of £200 for a few years back. It's been well looked after, set up by Brian Rodgers the respected Walderslade (UK) guitar tech, and fitted by him with a B-Band undersaddle and pre-amp system. The late Pete Hicks - largely a 12-string player since the 60s and well known in the southern UK - said the original owner of it did not realise how lucky he had been in getting it.

I largely only play my Mugen THE 78-12 now so I'd let it go for £300. No case.