Depends a GREAT deal on the type of rack you would like to use, the size, your budget, and more.
Most people use standard wooden equipment racks for their gear.
Others, myself included, use 19" metal equipment racks. The one I use is from Middle Atlantic, which is one of the largest rack suppliers in the world.
Racks aren't terribly expensive, but I use a lot of custom rackshelves to make it all look very pretty... and they get pricey when you use 10 or more of them. Along with blanks and other components.
I have some photos of my rack from a good 6+ years ago right here:
https://forums.audioholics.com/forums/threads/so-here-we-go-24-a-v-zones-w-10-sources.83272/
I've added a third rack since these were taken. I also have photos on follow up posts of a custom built-in I did for my family room area. That just used very inexpensive rack rail between studs in my wall, framed out to 19 1/8" between them. Total cost for the wood trim and the rack rail might have been 50 bucks or so. Took a week or so to put it all together. Once again, custom shelving and drawers and stuff cost a fair bit more than the rack.
At the end, it truly depends on what exactly you are looking for.
I've also bought a number of things online from places like Wayfair which have a huge selection in their audio racks and stands category...
https://www.wayfair.com/furniture/sb0/audio-racks-stands-c414565.html
For around $100 you can get something perfectly acceptable if it meets your needs.
