There usually isn't a ton of them out there, especially excellent condition. Just keep your eyes peeled and be patient. My '04 5 string SUB was easily in 98% condition when I got it 5 years ago. The original owner got it to have a 5er, but it never caught on for him.
Seems most that have these hold on to them. I came really close to selling my 4 string SUB, as a 2002 Stingray popped up locally a week ago. The SR was black, 2EQ, perfect neck, great frets and not too light nor heavy-everything I love. The temptation was to replace my perfectly good SUB with an equivalent SR. However, when I went home and played my SUB, it was clear that it was every bit as good as that SR (my neck and frets are great, it's not heavy) and getting it would just be me spending about $500-600 extra for a label.