Ya know...depending on how technically handy you are, if it *is* just the inverter and if it's a fairly common model, you can pick the part up off of eBay for usually under thirty bucks.
On the other hand, if it turns out it isn't the inverter, you're out the money.
I did some reading just to learn that it might be the inverter. Cheapest I found for screen+inverter assembly is sixty bucks. I'm still considering it.
As for my level of skill, I'll point out that this is a 390x built from the parts of two 390x's and a 390e, so I think I can handle the install. LOL
It's partly being cheap and partly being a hobbyist challenge.