You need to be able to get seeds into the soil. This will require killing your lawn with a spray treatment or mechanically tilling it up with machinery.
Once you have done either of the above you would seed in this fall or early spring.
Ernst seeds has mixes by region and soil type.
They take a good 2 years from seeding to really look like something.
WF seed will run you about 400-500 dollars per acre for a 10 or so species mix.
You could have them custom mix you something with less species to get the cost down, but you will have less of a bloom window over the course of the season.
To cut down on cost, you could reduce the area you plant to WF seeds and do a border around your property with something cheaper like buckwheat, clover, alfalfa, or sudex, and mow that a couple times a year and collect it for composting/mulch. Or leave your existing grass around the border.
Here is the one I used (It was slightly adjusted based on them not having a couple things and the cost was 45 per lb):
http://www.ernstseed.com/seed-mix/?category-id=283
They have a good section about establishing and maintaining a sowing of Wfs. It would tell you that you will get as poor stand if your do not remove existing cover (i would too).
Most likely, you just didn't see the highway crew spray or till the strips before planting.
They probably also hydro-sprayed the seed or used a drill to install.