Looking at your situation, what worked against you is that technicians always quote the full job: edges, base, structural work... but you don't really need to do it all at once. Deep scratches are more of an aesthetic problem than a functional one if they don't reach the core, and oxidized edges can be cleaned and sharpened without major work. Ask specifically how much it costs just to sharpen the edges and do basic base repair, without a full shop overhaul. Sometimes the quote drops a lot when you break down what's essential versus what's just recommended.
Either way, before you decide you need to think about how many weeks a year you actually use those skis. If it's just two or three weeks on vacation, fixing the critical points so they work well makes more sense than buying new ones that'll sit in a closet for 50 weeks. On the other hand, if you're planning to go skiing multiple times a season, investing in used ones that are already in better shape might save you headaches down the road.
Here's the thing nobody usually mentions: before you take your skis in for repair, try cleaning the oxidized edges yourself with a steel brush or some strong white vinegar. Sometimes the rust is just surface-level and comes off without a hassle. If after that you see they really do need professional work, at least you'll have ruled out what you can fix for free at home and you'll have a clearer idea of what repair is actually worth it.