You don't want to pay someone to replace the drive. You should do what KiltedTom suggested and get an external SSD. You can get an external SSD from OWC (MacSales.com), clone your internal drive to it and boot and run from it.
You could increase your read and write speed by 10X depending on the external SSD you purchase.
I recommend that you contact OWC's Customer Support and see which of their several offerings would best fit your iMac model, work requirements and budget.
Then when you replace your iMac with a new Mac you can take the external with you for external storage.
If you decide to go either the recommendations of den.thed and get a new Mac consider this: a 10 Core Mac Mini M4 with 16 GB RAM and 1 TB SSD ($999 + tax) with a 27" LG 4k monitor ($250 + tax from Amazon.com) is $1249 + tax which is $560 less than a similarly configured new 24" iMac ($1799 + tax) re 07/2025.
It'll be orders of magnitude faster than your current Mac.
