Take your car to either shop, whichever is more convenient.
Sales tax in Klickitat county (I’m not in city limits) is 7%.  My cost of operations in Hood River, in a zero tax state, is about 30 to 35% higher than operating in White Salmon. Start with a property and building that’s only 40% the size as the one in White Salmon but cost me 70% more to buy or lease.  Next utilities are 40% higher even though I’m heating and powering a building that’s only 40% the size. And then there’s personal income tax on all my employees working in Oregon myself included. These are all factors.

I have customers who want to have a repair done in Hood River to save sales tax. I get that.  However we have just balanced the scales to make repairs done at either shop the same price.  If a given repair is $100 in White Salmon with sales tax, it’s $100 in Hood River without.  So bring your car to whichever shop will either be able to handle the repair faster or is more convenient to you. Most larger repairs are actually done at the White Salmon shop anyway, even if you drop them off in Hood River.