Update: Got the idea on another forum to look at 0% interest promo credit cards. Got a few offers in hand then approached Amex and asked them what they could do with one of my existing cards. They were happy to slap a 0% interest rate on one of my cards for a year with a limit of $25K. Took about 5 minutes using their online chat tool. We will just throw all the big expenses on there and then pay it off either next tax year (when I can liquidate some additional assets without tax consequences) or after the house sells.
How long to save $25K? It depends on if you count retirement accounts. If you include retirement accounts then easily under a year, but that's a "lumpy" investment as we usually do big lump sum contributions to max out the Roth IRAs once a year (plus monthly contributions into 401K/traditional accounts). In taxable accounts we stashed about $10K-20K/year towards a down payment over the past few years while also maxing out retirement and saving for car replacements. Not a millionaire with a moon lambo or a DINKS household, just fairly high personal savings rates.
We have plenty of resources in taxable accounts right now, the issues are:
1) Selling equities will come with a big tax hit (probably enough capital gains to push us up into the 15% cap gains bracket for the year) and
2) Selling I bonds when they're making >9% interest would make me sad, especially as you can only contribute $10K/year.
We already burned through a bunch of liquid cash for a larger than expected down payment on a home as well as almost $10K in unexpected vehicle repairs and budgeting for the expenses associated with a cross-country move (probably looking at several K in gas alone). The house was a bit of a fixer upper, and we got the seller to make concessions (they came down on price, which is frankly a shock in this market) but we still need to come up with cash in hand today to pay for the repairs. Nothing extravagant, we're talking leaky windows, electrical, insulation -- boring stuff like that.