If your in Ontario and close to Toronto, you might want to wait for the April Toronto Reptile Expo. Here are the URLs for two breeders sites....it is the links page of each breeder. Not only do these breeders have amazing animals but so do the people they are linked to 
I bought my 1.5 group from Tarzets and i'm buying three more females from them this week 
http://www.painteddesertgeckos.com/links.html
http://www.reptilerascals.com/links.html
As for introducing another female.....First quarentine the new gecko for 3 months in a separate tank away from your current one. Once that is done, the way i did it was to set up a totally new tank for my girls (there are 5 of them so i set up a 40 gal tank) making sure to add all new hides (or you can wash them very well). This means that both geckos are going into a new environment and will not have set up any territories. Everything will be new to the geckos. Also you can just wash and rearrange one tank so that the female you have now thinks its all new.
I enjoy watching the interaction between my girls but i'll admit, there have been a few disagreements between them. Dot, my hypo is very bullish and if she wants into a hide where someone else is she'll push them out. Keep a close eye on them and if theres any agressiveness separate them 
I hope that helped 
Red 
>>Thanks for your reply. Wouldn't it be faily traumatizing for the gecko to come in the mail? Plus I live in Canada, I think they are all in the US.
>>
>>Lisa
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Crested Gecko Zeek:1.0
LEOS: Boo: 1.0 normal , Bronx & Nala: 1.1 blizzard,
Lily: 0.1 patternless, Abby: 0.1 albino, Zoe: 0.1 reduced pattern, Dot: 0.1 hypo
Chip: 1.0 papillion (small dog)