Buying Dynasty 200DX from Cyberweld.

I have a price of $250.00 for a full tank of 330cu argon, tank included
(sold to me) from the local Etox welding supply.
What is the shelf life of ARGON?.
Also to trade my 80 cu ft Mig 75/25 gas for fill is $22.00.

I have decided to go water cooled tig but not to buy the pakage as I wish to buy a "used cooler" different torches etc. I think the price will be a little less also, correct me if I am wrong.

Any thought on these prices.
Argon tank will have 5 yr. cer.

God Bless
John