Starting a new Contextual CPM, CPC and CPV Business

I have been supplying my customer with CPM popunder website traffics since January 2008, while selling CPM popunder I was making profit but didn’t think it was benefiting my customers greatly; this is why I planed from next month to offer my customers with Contextual Pay per Click CPC, CPM and CPV advertising campaign.

I would like to get some advice from smallbusinessforum members which type of campaign format you would like to use.

(1) Pay a flat rate for your Contextual Pay per Click CPC, CPM and CPV advertising campaign. ( For example only, 1000 Contextual CPC for $230)

(2) Bid for keywords for Contextual Pay per Click CPC, CPM and CPV advertising campaign. (for example only, minimum bid rate 0.05 for Contextual CPC)

I would here which advertising model you would choose, all comments are welcome and highly regarded.
Thank you.