Shopping cart customisation

Like to request for 2 quotes for Phase 1 (installation and initial customisation) and Phase 2 (based on specs). Pls recommend the most cost effective solution ie X-cart, LiteCommerce or Lite Commerce ASPE as I think all can do the job as well as the appropriate add-on modules to purchase. The deliverable are as follows : a) Phase 1 - Product installation and customisation to "look and feel" - end of next week. Single signon integration with MLM and webfront end - end of April. b) Phase 2 - based on spces - end of May.