Is the question "how long will it take?", or "how much do you think you will have to spend?"?
Either way, I'm in the age of 17 (been collecting since I was 16-ish) and have already spent over $2000 on VGM, and that's only for 20 albums. I recently bought the most valuable thing that was in my wish list before (Digimon World OST) - which I spent a little over $400 on (which was, and still is sealed, though). So I don't have that much left on my wish list that I'd pay gazillions for.
So, what's left in my wish list, that I'd have to give my legs for, is probably the famous Super Donkey Kong soundtracks. But I honestly wouldn't spend more than $400 on those -- even if they were sealed.