I actually struggled with this too when I was building my CTC. I have limited woodworking skills (and tools) and I wanted my CTC to look as nice as I could make it with the skills I have. Another TNTTT member actually encouraged me to make my own.
Building does cost a lot less than buying cabinets ( I didn't keep track, but I think the hinges and hardware were the most expensive single item (all together) other than plywood, but all said, I bet I spent less than $300 for wood, Paint, screws, and Glue).... but it is a lot of work/labor, so you have to be into it. I could have afforded to buy them, but I chose to build. For me, I am glad I did (thanks again Martin!)
In the end, I think they turned out well and it really does make the camper "mine" in terms of the overall custom build. Not another the same. I know every little flaw and can take pride in it... I would say that the cabinets I made are built stronger than most anything you can buy at Home Depot or Lowes. No particle board that swells with moisture and is destroyed by water. Everything is screwed and glued plywood... not.staples that may vibrate loose... Particle board is much heavier than plywood so the home made cabinets are lighter. They are also lighter because if done right, there is just the face, side and doors . You can use the trailer walls and ceiling for the back and tops and in some cases, the sides.
I know a lot of people buy their cabinets and that is fine for them... But since you asked... I just shared my personal choice to build.
Just a few pics of how mine turned out and I had no experience prior (maybe it a shows)... disclaimer.. I did buy the vanity cabinet in the bathroom because they almost gave it to me. It was an open box return that has some issue with the backside that I repaired. The medicine cabinet was also a purchase.. Was cheap.
One thing to also consider... building your own cabinets lets you build non-standard sizes and make best use of space in some cases. There was no good way for me to fit what I did in that Vnose with off the shelf cabinets. That was a big consideration for me also.
If I can do this.. anybody can when it comes to wood.. it is not my thing believe me. I'd encourage you to do it yourself.





