We have an independently owned camping/hiking store nearby called Sherpers that I buy stuff like that from. But Gander Mountain should have it. I think Wal-Mart does too. Yes, just reseal all the seams. Buy a couple of tubes, it's not expensive stuff.
2013 Jayco Jayfeather X20 E, 2008 GMC Sierra 1500 Crew Cab Z71 SLE