I am from Minnesota as well, and it really depends which casino you visit whether you get someone nice or someone nasty. Here are some of my experiences...

Fond-Du-Luth: A week or two ago I was up there with my wife for her work, and I stopped in for some chips. I played a couple hands, and then before I left, I told the dealer that I collected chips and I wanted to grab a fiver for my collection, but the ones I had left were chipped pretty badly. He took the time to look through his rack for a nice one (which I tipped him a dollar for).

Jackpot Junction: On my way home on a day trip, I stopped in for a one and a five. I asked the dealer for a couple chips, and he gave me a weird look, and said, "you want a one and a five? Really?" He eventually relented and gave me what I was asking for.

I've collected chips from both Grand Casinos, Treasure Island, Mystic Lake, Prairie's Edge, Fond Du Luth, Shooting Star and Jackpot Junction, and never had a problem. I've never had a dealer refuse a request, but I'm never asking for more then 3-4 chips at a time. At worst I get a strange look. Otherwise, I usually put down a 20, play a hand of $3 BJ and then walk away with what I need. It always helps to play (ahem LOSE) a couple hands of blackjack to get what you want.

By the way... if you have access to chips from the northern casinos (Seven Clans, Northern Lights, etc.), I'd be willing to trade!!