diaper bag dilema

So I have my heart set on the Oioi diaper bag. It's black, big, fashionable, rocker-ish and modern. It fits perfectly with my style. The only drawback is, it is $160. I can't bring myself to pay that much for a purse/bag/diaper bag whatever. I search for it on ebay, craigslist and other random sites, but still it is always around the same high price.
This bag seems to have it all, interior and exterior pockets, easy wipe interior, change mat and insulated bottle holder included. It also comes with stroller straps and a longer strap so you can wear it across your body, helping with my "purse shoulder" problem.

I was thinking of just getting cute hobo bags/totes that have a lot of interior pockets then purchasing a travel diaper changing kit like this one, and getting an insulated bottle pouch like something found here and just putting them inside the purse. Then I can purchase different purses that are cute and still functional and can use many of the purses I already own.

So, my question to you: have any of you tried to use your own purses and just get the extras to add in, or did you find that you really did need a good quality diaper bag with all the pockets overall?

♥ Michelle