Also rather than swapping to the cheapest kit have a look at other ways to save on brew day.
Di-San from Aldi is $2.49 a kg, and makes an awesome cleaner.
Reuse your yeast multiple times (assuming you are not using the kit yeast)
Buy your LME in bulk packs
Order hops online.
http://www.yakimavalleyhops.com does 2oz bags. You just need to order up a lot (3.5lb) to make the postage viable.
The other thing AG ingredients can be a lot cheaper than a decent kit. My house Aussie Gold is about $10 a batch if buying ingredients in bulk.