Jack the car, remove wheel, remove the caliper, re-fit wheel, lower car
That way you only need a small space to rebuild the brake
The shop may have been quoting worst case, if the pistons need replacing etc
I have the part number for the seal kit somewhere. Think they are only $40-$50 a kit. Should be fairly easy to rebuild. Hopefully the most they will need is a light hone.
Otherwise you could buy a second hand caliper