Good Offer Or Insult

There is a 2000 double wide redman in the greentree list, it appears to have about $6,000.00 in back taxes
would $15,000.00 be to much to offer or would it be a insult.

Yes I am new to all of this, but I beleive that I would be responsible to pay those taxes if I was the high bidder to green tree.

Any ideas or input would be greatly appricated, I am South Texas

Thanks