I'm perfectly aware the adviser is not the payer but I would hate spoiling a whole batch of seeds.
I use several heating mats, heating cables coupled to a thermostat.
I suggest the following links about temperature. Personnally I aim at a germination of most seeds in 3 - 4 days, which means the highest recommended temperature. I sometimes cool down a bit at night.
http://www.tomatoville.com/showthrea...927#post542927
http://tomclothier.hort.net/page11.html
All the best
Loulac