MobileMe vs iLocalis

mobileme available in ebay for around $50-$60 or less if you are lucky. Not familiar with iLocalis so cant help there.

I purchased MobileMe on amazon from a reputable seller for $50 and personally think it's worth the security for our iPhones and bonus features (iDisk, gallery...).

if you only want GPS location....

GPS Location only: I have been using the PlaceTrack (cydia app) that uses Google Latitude and is been working pretty accurate for me and it doesn't use too much battery. It doesn't have any of the features of the other two you mentioned just GPS tracking, but if you just care for the GPS location of the phone only, then a one time buy (i think is like $2) is another possibility... I think Latitudie (app store app) works similar as PlaceTrack but is less as accurate...