That seems extremely high for a 20*40 liner. Unless you are out in an area when pool professionals are scarce, I would continue to call around. Regarding your liner and leak, have you allowed the water to continue to leak until it stops? Maybe you can find the area in question. Are the 9 patches around the seam, or they were tears in the liner, patched up, here and there?
Reminds me of a tree that is being taken down next week. First quote was $4,000. Second quote was at $2,000, but they would leave the wood on my property. After 6 quotes, I am at $1,100 with the stump (Legit company that has insurance and replies to e-mails). Most quotes were at $2,000, but one person was at $1,850.
Patience is key, but it appears you may not be able to be patient on this one. You may look for experienced individuals who work for pool companies, that install liners and work on the side. Ask friends for referrals and just keep digging. I have been planning my liner change since the day it was installed, which is early, but at least preparing yourself is always best.
The liner replacement for my friend was $3,900. It is 28 mil and the pool is quite large (30,000 gallons) free form (25' * 44'). The foam was $200. The liner track was included, but the water was completely dumped. Do not know what the water cost, but assuming like $300. Also, check the local community in Sunman to see if there is a community Facebook page, etc. Good luck and keep us posted!