I only needed to replace my seals front and back. I went to an automotive glass place and they gave me the name of their supplier. The supply house sold me 50' of gasket (self locking too) - I had to do it by myself, but well worth the price. I only paid $.90/ft and it works great! It is not the easiest job, but a lot less expensive than to have it done.
I did talk to several rv places before hand, they all "farm" the jobs out - so I went to the glass places, I don't think they liked rv people very much
Most of them thought we wanted the job done cheap.
Have about 25' of seal left, if you are interested.