Second-hand GPU is definitely go down in price. 3060 Ti second is around $300 or cheaper here. Even the series 20 can be obtained quite cheaply (there's someone who claim that they get 2070 Super for just $200, although this listing is a rarity). The AMD RX 6600/6650 XT is always a really nice budget GPU(they're the winner for fps/$ for 1080p and 1440p). There's also a rumor about intel arc 750 being discounted to $250 now, although you need to check for this yourself. The 16xx series is also quite cheap, though obviously the upgrade might not be as big as you hope.

Ethereum's move to PoS basically made GPU mining almost unprofitable, so there's tons of second-hand GPU flooding the market, and if you/your hubby knows how to benchmark the GPU they're usable (Mining rig usually undervolt the GPU so they're often just as good as normal second hand GPU, but not every miner takes good care of their rig).

There's actually 2 listing on eBay for 2070S under $200, but they look very sketchy.