You can get the previous generation devices they are called av500 except by tplink who call them av600.
The newest ones are generally called av2-600 or 1200 but you also see them called 1000 and 2000.
The older models might save you a small amount of money but the new version work much better. They are faster but much more important they work in many houses where the older devices have problems.
Not sure that is not a bad price, it is for a pair of units.
Although it is not recommended you can use very short extension cords with powerline. Mostly the ones that cause issues are thin cords that are more than say 6ft. I have run them on a 50ft heavy duty extension cord (no 12 wire) to test and they worked fine. Powerline is...