I personally have a few resellers and I use 1 for when I sell websites, almost all the domains in my signature are all one 1 hosting account with Add On domains heh.
So reseller costs mid XXX per year, or multi-dom early XXX if your not likely to use the multi accounts then I'd go with multi-dom.
For example in dreamweaver, I open 1 project and I have like
skindustrial-
-dom.co.uk
--images
--includes
-dom2.co.uk
--images
-dom3.co.uk
--graphics
--images
--uploads
making it easy to work on them all at once, this also means I can connect once with my FTP and upload to them all making maintenance (i can never bloody spell that) easy as pie.
I trumpet EvoHosting all the time
http://clients.evohosting.co.uk/aff.php?aff=060 (aff link), remove the aff link or leave it on

, I have that mapped to a shortcut coz I promote them so often

At the mo use the discount code snowplough to get 20% off every month/year/biyearly on shared hosting. 2 yrs hosting with 20gb diskspace/400gb per month bandwidth, unlimited sites, for less than £100 a year with the discount is a winner
