The foam floor tiles are good and last anywhere from a year or so to a decade depending on how often you use the workshop and the type of work you do. Rubber anti fatigue mats are even better and last way longer (I have some that are over 10 years old and were second hand when I got them).
A cheap and cheerful option that works great is carpet swatches. They are between 2 and 3 feet square normally, edged nicely with a binder. Go to your local carpet showroom and ask if they have any they are throwing out, they almost always do as patterns, colours change all the time. If they don't and you are not in a rush, leave your number. If you do get some, trade for a pack of beer or something and you will always get new ones. They last for years and are super comfy and warm, if you drop an item it doesn't get damaged.
I have some extra thick axminster wool squares I got almost 15 years ago, they look dirty but they are still in excellent condition and very comfy.