I've never used TIs - too rich for me, and I've always been very happy with Deep Talkin' Flats with an occasional side of D'Addario Chromes.
The very best prices I have found on Labellas have been through Imperial Guitar in New York and Bassstringsonline.com. The latter site is owned by an active member on TB and he has been excellent about customer service. I had one string break due to my own error - accidentally tried to put long scale on a short scale bass - and he replaced the entire set with the correct length and just asked me to mail back the others. I know that he sometimes replaces individual strings for customers.
There are other strings made with flat material on a round core, and I'm not aware of any systemic problems with them, so I'm not convinced that's something I need to be concerned about.
Imperial Guitar:
http://www.imperialguitar.com/ Check this - the 760FL set is $28.55!
And these guys have also special-ordered Labella sets for me when I called and asked - still gave me a great price.
Bassstringsonline:
http://www.bassstringsonline.com/ Note that the 760FL set is $34.95...still a really good price. At this site your money supports another bass player.
Juststrings.com is $35.81 for the 760FL set.