I don't have a clear concept from your description as to where these plants would be located but I believe what you are looking for is a creeping thyme rather than the culinary types you describe, which tend to be much more upright, almost shrubby growers.

Groundcover/creeping thyme seeds are not that hard to find nor are they that expensive - look here. You can also split pots of creeping thyme and spread them out to get more bang for your buck. Most cultivars root as they grow. Or just go with a wider spacing and be a bit more patient with the spread.

So, I looked at your link and their prices were $150/lb. How much would I need for 150 square feet?

You need 1/8 of a pound to cover 5000sf - that's only 2 ounces! The 8000 seeds for $9.99 from Amazon sounds like a pretty decent deal to me and should provide you with plenty of surplus in case germination is spotty.

Hello. I've been growing creeping thyme and having pretty good luck with it. You can buy it on Amazon for about $10 for 1,000-10,000 seeds depending on the dealer. I got the standard pinkish thyme and the magic carpet red colored thyme. My method was to start them in starter cups and overseed each cup. I used MiracleGro Starting Mix soil and I sprinkled about 20 or so seeds into each cup. I put them outside in the sun during the day and brought them inside at night. About 50% germinated in 4-7 days, which is plenty. After a couple weeks I put them into 4" pots and a couple weeks after that I placed them outside. They were around 8" round tiny bushes. Only 2" high or so. They have since been expanding, or creeping as their name implies. Next year I hope to see them bloom. I may start more in late winter so they will be ready by spring. I still have a ton of seeds leftover to play around with.

Jabber,

I would like to try magic carpet to replace a small lawn. When you put 20 seeds in each cup, do you separate them when they grow bigger or when you move to 4 inch pot? I' m trying to start the seeds in February so that I can move them out by April. But I'm afraid the weed will take over the thyme since weed grow much faster.

Thanks

This is my Thyme garden

https://theherbladyblog.wordpress.com/2017/03/20/my-thyme-garden/ 

Unfortunately they can't be grown from seed. You will have to purchase mature plants and divid.

Wild thyme can be grown from seed. Also German and summer thyme

https://theherbladyblog.wordpress.com/2017/09/05/wild-thyme-in-the-adirondacks/

"Unfortunately they can't be grown from seed. You will have to purchase mature plants and divid."

???? Not true!! Many kinds of creeping thyme are available by seed.