Sometimes you can find older model shifters on eBay. The one you want is available new but from China. I've bought parts from China in the past when they were outrageously expensive here like a derailler hangar that sells for $30 at one store I frequent but sells for under $10 online. If they ship by "Speedpak" shipping it gets here reasonably quickly but if they use China Post it takes agonizingly long to arrive. Check out this Chinese seller who has the right side shifter which should be your rear shifter. Compare the picture with what you have now. Not cheap at $48 but it may match your left shifter
https://www.ebay.com/itm/403049417498 The 9 speed version seems to be really hard to find in the US. A fair number used are on eBay from overseas sellers at reasonable prices like this pair
https://www.ebay.com/itm/275856934079