Karyn, can you please post a direct link to these? Thanks!

Direct link. Look under heating.

Here is a link that might be useful: The Bean Farm

That is a very good deal. I have a reptile mat from Zoomed that is way smaller and cost more than that. It has lasted quite awhile now but a larger one would be nice.
I also had 2 heat mats from Hydrofarm that burnt out after about a year so don't really want to get anymore of those.
The Ultratherm mats that are 11 x 35 would be about perfect for my plant/seed starting shelves.

I bought the Flexwatt heat tape, 12' of it for around $70.00. It's been a life saver for me. Love it!

I use heating cables under the tables in the GH and that's a much more economical way to go but I can't use them in the house. Do you use the tape in your house or the GH?

I've had a few Hydrofarm mats that have proven to be pretty low quality and another whose maker I can't remember that's marginally better. My commercial heavy rubber mat is at least 8 years old and works great but takes up so much space. I don't need 18 sq ft of bottom heat inside but did want more space then the average mat had. These Ultratherms came in a nice range of sizes and so far I'm really happy with it. The heaters made for reptile cages seem to be a better quality then the ones made by Hydrofarm and the like. I have a few small heat mats in my gecko cages and haven't replaced them in 7 years. BTW the Ultrathem mats are a few dollars less expensive when you go thru Amazon as opposed to going directly to the Bean Farm. I paid $30 and the same size is $33 direct.

I used the heat tape in my basement. Helped alot! Never thought of going through Amazon or Ebay!