Is it too much to ask my groomsmen to purchase a bespoke suit for my wedding?

I have already gotten my suit made at a very nice tailor in Chicago who offered to make suits for my groomsmen and other guests for around $800-$900 for a standard black three piece suit if I had at least 10 people.

My groomsmen are not fashion minded people, they would just as soon rent a cheap suit and call it a day. I asked them that they purchase a bespoke suit because

1. I don't want them looking like shit at my wedding, and

2. I am the first in our group to get married and we are all in our mid 20s. They are going to get a lot of use out of this suit in the future.

They are not objecting all that much, perhaps they just aren't saying anything, but my two brothers are groomsmen and they have no money at all (college students) so my family will have to pay for theirs. My family has the money, but they are really trying to convince me to reconsider if this is all necessary.

My dad and grandfather are saying just get a cheap suit and have it adjusted and I feel like a pretentious ass insisting they get a decent quality suit for my wedding and explaining that $800-$900 is an excellent price for what they are receiving.

Am I being an asshole here? Should I just give up and tell them to do whatever they want? I really don't like having to insist they spend this much money but I think they have just never seen or worn a well-fitting good quality suit so they don't even understand the difference. And now I sound pretentious.

Any advice?