It's not much, I would be suprised if it was more than a pound as an 18k Vector compact self contained unit holds 17oz according to the spec sheet.
Why does it need a recharge?
Will it need to be checked for leaks
If it has no leaks
then it will need a good evacuation with a quality vacuum pump
prior to recharging.
R410a will fractionalise when it leaks, so the remaing charge will have to be recovered and disposed of.
A R410a system is relatively new, inside 5 years I would guess.
R410a is very cheap
refrigerant no where near $200 a pound, more like $5.