You don't say how long you've owned it and whether current performance is a recent change. My '97 Corolla has a five-speed and low mileage, but I kept couple of American cars with automatics going through deteriorating seals and smoothing jerky shifts with those ATF helpers. In particular I liked Moly products, which enhance lubrication using molybdenum disulfide (google it, and check the Amazon comments, etc.):
Liqui Moly 20040 ATF Additive
Since letting any shop inside an automatic transmission, or a rebuilt, is likely to cost more than the market value of the car, I'd try a dose of moly before giving up on the tranny. Note that Moly also makes an AT Fluid replacement, costs more.