My husband and I were the grateful recipients of a 13 year old used Gibraltar pool last year. We dismantled it very carefully and have been storing it in pieces in our basement for a year. We're in the mood for a project, so we started gathering an action plan to get this big thing up and have come across a million questions that don't seem to be addressed in the installation manual. The first is the liner. I see that Gibraltar sells one for around $1000, as well as several companies that sell liners of the same size but without guarantees that it will fit my 13 year old Gibraltar. Anything in particular that I should be looking for or a price point that will give me a decent liner? Thanks in advance.