$100 minimum deposit requirement is indeed high for a deposit bonus campaign. Minimum $20 deposit requirement is reasonable for a deposit bonus promotion. Although 200% deposit bonus is tempting with 25× wagering requirements only, but OP hasn't mentioned that how the wagering requirements will be applied. Probably the wagering requirement is applied to the total sum of deposit and bonus amount.
I agree, a minimum of 20 or 25$ would be better for me. The wagering requirement I can understand, that is similar for a lot of sites who offer deposit bonuses. Normally it is around 35x, so a 25x wagering requirement is acceptable but never easy to do.