Well hopefully if the customer has 100000 domains to park (that they paid for) then maybe they should have that much more of reason to have a better budget for a server

Only reason someone would use the server with aloaddddd of names would be to take advantage of the system and save money, in this case someone with 10000 or even 1,000s domains wouldnt really be worried about saving $5 lol.

You should be fine with unlimited parked domain, but choice relys with you :p

(worry about space/bandwidth).