If I had heaps of cash, I'm not sure I'd move, but I'm 100% sure I would have our basement dug out and finished. I would also get more insulation and some sound proofing put in.
But just 500 more square feet, that would be lovely. I need to price putting up a winterized shed versus getting the basement dug out properly. LIke dug, underpinnings and a proper concrete pad and some plugs? We could bung all our tools down there, Wouldn't even need anything fancy.
Because a winterized shed, plus some electrical out there,? That couldn't be cheap...
That said, my sort of dream is to build a shed out of SIPs just, you know, to have done it (cause they fascinate me).
omfg SIPs roofing panels! omfg. OK CAMERON YOU HAVE TO GO BACK TO YOUR WORK STOP IT DOWN THE RABBIT HOLE
Honestly, new windows (which I guess we're inching towards) would make a massive difference.