I do a monthly mailer myself. I do bulk mailing, but that has to be 500 or more pieces to get the discount.
In my opinion, direct mail is worth it if done correctly. My bulk rate is 24 cents a piece.
Get yourself a regular farm of at least 500 homes. Then your free to tack on any other mailing things you want to try. For instance, I will be doing a buyer only piece in Feb to about 300 apartment units. Since I already have over 500 I do monthly with other farms, I will still be able to do them with the discount.
An interesting note is that I have been getting really good results with my mailers. I only started them in September, but have gotten about 4 leads per month from them. Way more than I figured with the current market and season.
I also walk a farm area of homes. These get a newsletter delivered to their door. I don't knock, just leave the item. I do these to about 300 - weather permitting.
My single suggestion is to create an original piece to send out. All the "easy" ways (IE: using a NAR template or some service that creates your content for you) might feel like a deal, but the stuff that really seems to work is the stuff that I make myself. My currently mailer is an 8.5x11 sheet folded once with listed and sold data for that homes neighborhood along with data about the city and county. The key is making the piece specifically relevant to the person your sending it to.
Good Luck
R