Soldered RAM upgrades cost $80–$200 if you find someone good.

You’re not going to get a reliable upgrade for $50. That’s the “I’ll try it with a hot air station in my garage” price, and you probably don’t want that.

A proper microsoldering job on something like a MacBook or ultrabook requires decent equipment, steady hands, and the right BGA rework station. Shops that do this charge for risk and skill. $100–$150 is the sweet spot for most machines. $200+ for rare laptops or tricky board layouts.

Does that sound high? It’s still cheaper than buying a new laptop, and it actually works.

The cheap option is “buy a machine with enough RAM in the first place.” Soldered RAM is a lousy way to save $50 at purchase time.