In order to not do a lot of replacement of equipment I would plan out a finished system and do a modular build.
1) Size - 5, 10 or more gallons.
2) Type of build - RIMS, HERMS, 3 kettle single tier, gravity fed, BIAB, 2 kettle etc.
3) Power requirements for finished system - 1 x 5500, 2 x 5500, 1 pump, 2 pump, etc.
4) Control options - 1 pwm + 1 PID, 2 PID, BCS or brewtroller or other
5) Modularity of build.
For example, I started using two coolers and a propane fired boil kettle using a 2 tier arrangement with manual lifting. I had a kettle large enough for 10 gallons, but limited myself to 5 to begin with. My process with propane was to heat strike water in the boil kettle and use a bucket to transfer it to my cooler mash tun. While the mash was converting I heated sparge water and transferred it to the cooler hlt which was higher than the mash tun. Fly sparged into a bucket on the ground and poured it into the now empty boil kettle. After the boil I drained it through a CFC into the fermenter.
In switching to electric, I envisioned a system similar to this 2 vessel RIMS system
. I bought a 50 amp. spa panel and installed it in my brewing area powering a 4 wire range outlet. I fed it from a 30 amp breaker in the main panel with wiring sufficient for a 50 amp circuit. I decided on a BCS-460 for control and purchased an electric cabinet large enough for breakers, SSR's and contactors.
I first built a simple pwm control and put a 5500 watt element in the brew kettle. With this I was able to use the exact same method but could now work indoors while waiting for the finance committee to approve continuing work.
Next step was to get the BCS and all other SSR's and necessary breakers and other items for the control cabinet. After wiring this up I switched the 30 amp breaker in the main panel to a 50 amp breaker as I now had a 30 amp breaker in the control cabinet to handle the boil element. I continued brewing with my first electric method but switched from a pwm circuit to the BCS for control.
Finally I built a single tier stand, finished the 5500 watt RIMS tube and installed the pumps and piping. That left me with a pwm circuit, an extra cooler that had been the hlt and a 30 amp breaker all re-purposed by now. This took me almost 2 years to complete, but I didn't interrupt the brewing cycle at all.