Obsessed? (maybe just a little!)

Gavin has this thing going on for Thomas the train. I guess I shouldn't say thing, it is an obsession! He insists on wearing his Thomas PJ's every night. The problem is that I only had one pair until recently. Now we have two, but that is still not going to cut it. He throws the biggest tantrum you have ever seen in your life when I try to take these PJ's off in the morning. He has Thomas shoes as well. He wears them constantly and takes a nap with them on. He lets me take them off at night now, but it is still a struggle. One night, I left the Thomas shoes on his dresser. When he got up the next morning, he had put the shoes on himself in the night and slept in them!
This has been going on for months now! The girls really liked Princess stuff, but this is a whole other level of liking something. He now has Thomas sippy cups, a Thomas swimsuit, a Thomas sweatshirt (that he wears constantly!), and several Thomas trains to play with. He wants to watch Thomas all the time too. Luckily he will also watch "Chuggington" (if you don't know what that is, you are lucky!) on the Disney channel.
His obsession makes buying things for him very simple, but taking things off or away from him a nightmare! Every night I ask him to get his PJ's on and he says, "Choo, choo?" It's worth it for me to do laundry more often just so he is happy. I don't know what I will do when his shoes get to small. CLEARLY I should have bought a pair in several sizes!
I am thinking it might help with potty-training though. The girls did good with princess underwear, so I am hoping the Thomas underwear will work for Gavin!