Ah, I completely understand what you mean about ambition and expense. Top of the line configurations definitely are expensive and time consuming to put together.
If you are just looking for an “off the shelf” configuration, my recommendation would be to almost approach it like a gaming PC rather than a workstation as the markup for workstation hardware can be a big one and for most projects, a decent gaming PC is more then enough. Of course anything you get will need to meet the minimum requirements for SketchUp but I recommend going for at least the recommended requirements.
The minimum requirements can be found here: https://help.sketchup.com/en/sketchup/system-requirements
If you do decide to get a PC either built for you or an off the shelf configuration from a service, I can’t recommend any particular service or vendor as that would violate company policy, but I can say is that my personal gaming computer is still able to meet the requirements for SketchUp and do decent enough renderings quick enough for my needs.
Reflecting back on my PC configuration, I would do things differently in a few areas, but I am happy to share my thoughts below so read on and hopefully you can get some wisdom via my mistakes and save some time and money.
First up, don’t overdo it on a power supply. It is tempting to get a big one so you can potentially use multipe GPUs but in terms of getting the most out of your money, a single nice GPU is better than 2 mediocre ones and uses less power too. This means that you don’t need a monster 1500 watt power supply.
Second, if you are doing 3D design, CPU speed is more important than core count. You do not need an industrial strength CPU with 64 cores and a liquid cooling system. A nice 8 core or 16 core cpu with a 3+GHz speed is good enough and a decent heat sink and fan or AIO cooler is just right and will last a decent lenght of time too.
Third, 16 GB RAM is probably enough but I personally went with 32 GB so I have more than I need and won’t have to install more later. It ended up saving me later on when I had a program I was working on ask for 24 GB of RAM as it was loading a large file. Still didn’t end up needing the full 32, but if I had only had 16 I would have been out of luck.
Fourth, get 2 hard drives. If you are building on a budget, I suggest an old school spinning disk drive to store large files. It is cheap enough to get a few TB of storage no problem) and a M.2 or SSD for your operating system. This configuration keeps costs low and gives you plenty of storage on a standard drive while allowing for faster updates and booting speed via the SSD or M.2 drive. If money is not a concern, a M.2 drive and SSD combo is a technically faster at saving data but again, less budget friendly.
Finally, GPUs can be the trickiest part to figure out. I am still rocking a 1080TI and am quite happy with it but I hear good things about the 2080 series for rendering but I can’t comment on it personally as I have yet to try it myself. Real time rendering apps like Lumion or Twinmotion require a pretty strong GPU too so if your workflow includes one of them or a program similar to them, don’t go with a budget option.
Anyway, I have rambled on long enough here. Hopefully you can find a vendor in your area that can help you out if you go with an off the shelf model. I am lucky I live an hour away from a Micro Center so I can usually just hop in my car and get what I need when i need a new part for my PC. Although I hear they have good shipping these days so it might not be as big of an issue as it used to be.