2007 Equinox 3.4 transmisson issue

I have a 2007 Equinox with a 3.4L V6 auto transmission, with about 162,000 miles on it. Lately the transmission has been acting up once the car warms up and has been driven for a bit. The shifts will get rough from 1st to 2nd and 2nd to 3rd, and will occasionally miss with the engine revving up in between gears for a sec before it goes into gear. It'll also pause when shifting out of park into drive briefly before engaging with a clunk. The problems are at their worst when driving in stop and go traffic and the transmission having to downshift a lot, which sometimes it doesn't act like it wants to do or also does so with a thunk. At highway speeds it seems to do okay, or on cooler days, or starting out first thing in the morning nothing will seem amiss, but after being driven in town for a bit it acts up. Unfortunately it's a sealed transmission so I can't even check the fluid without having to remove a bunch of stuff to get to the well-hidden dipstick, and a transmission shop can't do any more than change the fluid without breaking open the whole tranny, which they said they would do a rebuild with so many miles on it, which will cost me a ton of money.



Is there any thing else I could do? Spend the money for a rebuild, or just get a used one for all the miles the car has on it? Or is there another, cheaper solution?