There are multiple was to send flyers, so you really need to narrow it down.
Direct mail/bulk mail: you need create or buy a mailing list, print post card and pay for bulk mail permit through usps. This one cost more per card but is very targeted and you can send to just one house in a neighborhood if you want.
EDDM: Cost of postcard + .177 per card = (cost per card). Not as targeted as you have to send to an entire mail route and can not just send to one home. This is also sometimes referred to shotgun mailing.
Send Jim: High starting fee i believe, one guys spent 2k to sign up (I think he got a plus edition, not sure).This is also very targeted and you can send to only one house if you want. They also have a feature called radius bomb in which you can send just to certain neighborhoods or house. You can also take a picture of a potential customers house and on the post card the picture you took will show up making the cards very personalized.
Diy: get a flyer/card printed and put a stamp on it and send you self. This can get time consuming if you want to do a big mail out as you have to write out every name and address. Total Cost = card/flyer price + .49 stamp.
And there are other ways to do mailings, just look it up