Costco
Edit: When you say small run, how small do you mean? Like 10? Or 200? If it's real low, cafepress might be your best bet
For Costco:
180-1079 mugs = $1.19 a mug
Ceramic Mug - 200005
Screen-printing Set-up Costs:
$35 set-up per color.
Run charge: (per piece)
Item price includes one color, one location decoration. Add $.40 each additional color per piece.
Must be ordered in case packs of 36, with a minimum of 5 cases (180 units).
Artwork: (uploaded image only) $25 charge for art conversion.
I'm not sure if the $35 setup charge per color applies to the first color. If it doesn't, the cost for 180 3-color mugs would be:
180*(1.19+.80) + $70 = $428.20