Stock floor mats should last the average daily-driver around 10 years / 150k miles of driving. If your current mats are from 2001, you've done very well
If you need to purchase rear
mats, generic "compact vehicle" aka size small, will work just fine. It's a simple $16 (from pepboys/autozone) replacement that look and work just as well as stock rear mats, for only a fraction of the price.
Also, a really good vacuuming followed by a thin layer of Fabreeze on the floor and the mats, then left overnight, will get back an almost "new car scent" for a good while. Don't let the Fabreeze set on your plastics or leather areas - simply wipe it off with a dry towel if it does.