As Gadge said you can make do with a small unit, preferably one with a heater to heat the solution. Most of the cube carburetors will fit. I did my work with a 2.5 Liter unit for several years just had to deal that short timing period. My business lead me to larger carburetors and the need to let the unit sit unattended for longer cleaning periods so I upgraded to 6 liter unit that way I can cleaning a carburetor while working on another project plus I now have adjustable heated water temps. Most of my small carburetors including ATV carburetor fit in it.
This was what I was doing Saturday here. I set a 30 minute cycle while taking care of customers that swamp me. All week no customers then Saturday they came from all directions. I even had one to show up Sunday @ my home. Not going to be able to work on it until probably Wednesday as it going to be raining for tow days here. I got a $350 carburetor that going to need a bushing machined for it. The choke had worn complete in two. Now I got to enlarge the shaft hole and install a bushing. Still cheaper than buying that expensive carb.
As for cleaning just beware to more crowded the tank is less effective it is. Also those plastic baskets will absorb about 20% of your cleaning power. Personally as starter unit I would recommend starting with a 2.5 liter with heater. Another trick to save on the expensive solutions is place items in a smaller sealed or unseal (depends if taller than the rest of the tank's solution or not) container with the solution and fill the tank with plain water otherwise. Personally I usually clean with household liquid dish and water. I do have stronger soaps pH wise but don't use them much unless I planning to store the carbs for a while as they non residual soaps. With regular soap you need to do a rinse cycle using plain water and lightly blow dry the carbs being carefully not to blow out any of the check valves.
This what I did and then when I got ready to upgrade I sold the 2.5 liter (well taken care btw) for 50 % of what I paid for it to another start-up tech and applied that to the new unit's cost.
Final pieces of advice don't mix incompatible chemicals in the unit as some can damage the tank and carbs themselves plus some can produce toxic fumes. Also don't let the cleaning solution just sit in the unit as some tanks even when they to stainless steel (very low grade of stainless steel) will rust. My 2.5 liter tried to but I caught it in time to remove the rust. Another thing to preclean the carburetors by removing all the loose exterior surfaces. You don't want trash migrating into carb that you can prevent.
