Bulk Mail Marketing Advice - Vendors and Methods

[Weina Shi]

I am new to direct mail marketing and my goal is to find 5+ unit apartment buildings in my area as long term holds. Do you guys use USPS bulk mail commercial account which is $225 for initiation and $225 per year? Or do you use a third party vendor who does both printing and mailing? Any suggestions for vendors? What's the most cost effective and efficient way to do this? I plan to send a letters and post card marketing pieces. Thank you!