If you make upgradeable weapons farmable that would be wrong to the old players that had to buy them; I am however not against having them on sale in the item mall.
Make upgraded weapons farm-able in game. (slow process available for all lvls)
Have upgrades sales, reguarly and with a similar cost as the old upgraded weapons
Do not change anything about the current state of the game
A combination of option 1 and 2, which would include sales & farming the weapons
If you make upgradeable weapons farmable that would be wrong to the old players that had to buy them; I am however not against having them on sale in the item mall.