You can respray them yourself but it does take a lot of patience for cleaning, masking and spraying and some good know how on how to and where to blend properly so it looks seamless. It can be done well but unless you spray everyday, you'll need some practice. It helps too to start w/ your smallest repairs first and practice practice practice before moving to larger ones.
Wurth Silver (Silber) matches when you lay it down right and then clear. I think 1 can of color is supposed to do 2 complete wheels but my advice is to buy at least 2x the silver of what you think is needed. Then practice A LOT off wheel until you're 100% comfortable in how the silver flake lays down so you can match the existing. This way you will not run out in the middle nor feel rushed to start spraying for real. It'll be easiest to take the wheels off the car and work on them at table height too. Your back will greatly appreciate it
Now, if you only have scratches that aren't all the way thru to the paint, consider instead just wet sanding (w/ 1500 or 2000 grit w/d) and polishing to bring them back up. The clear coat is tough and comes back nicely w/ a little bit of work.
Good luck