$10k USD - That seems to be the current market rate for an 85 kWh used/reman/salvage replacement pack that gives the owner a rated range of around 240 miles. Just the pack. Any applicable labor, taxes, and warranty (explained below) are extra.
$10k includes Tesla, 3rd party professionals and salvage yards. Tesla bundles in a 4 year/50k mile warranty while others offer warranties at an extra cost. Each year of warranty seems to range from $1250-$1500/year. e.g. Tesla's basic $15k=$10k pack + (4) x $1250 warranty. Of course, Tesla does not break things down like this, but based on 3rd party warranty fees, a reasonable comparison.
So your decision around that magic $10k number for a 85 kWh used/reman/salvage replacement pack revolves around warranty and convenience of location/time.
Lastly, Tesla is the only one providing new (not reman) replacement packs. $18k base plus tax, labor, etc for around $21k total. Comes with 4yr/50k mile warranty. This is only option (unless you get a 1-2 year old salvage replacement pack) that will give you the original rated range and slightly faster super charging speeds.