Filters - ATF Service - Any Suggestions

I would like to change all my filters in my 98 - 163K on the dash. I figured buying from MB dealer would be a little costly, so is there another place I could purchase all the filters for less of a cost. I was considering purchasing 8 qrts of Mobile 1, than having the oil changed than doing the filters my self, also what is the general cost for a ATF, I think I need it thank you