Excellent thought! I had the same concern 5 years ago, when I realized that in every hardaware change I had also take in considaration the famine of the integrated PSU. Which was a pain in the ass changing PSU's and some time cases. My wallet was getting from thin to thinner!
Before going outthere and buy one of theese "boxes" you might think a little bit further
a. buy a general use AC/DC psu or a plain transformator to stepdown to 24 VAC.
2. use some extras power regulators (stepup/stepdown)
3. some electrological equipment (cables, aluminium box, irrigators, etc)
All this is going to cost significant more less, with no fear of depreciating your investment.
Just for the beggining.
Define max Watt consumpition (110 VAC / 60 Hz to 25 VAC / 60 Hz for 6 Amperes will result satisfying 660 Watts, or 220VAC / 50 Hz to 25 VAC for 5 Amperes will satisfy the demand for 1100 Watts, for continious operation, add a 25 % in the current in each case for start / peak instances so instead of 6 or 5 Amperes use 8 Amperes).
There a lot of drawnings reffering the making of an excellent stabilized output. Irrigators will avoid the need for fans if they' re used dor cooling power transistors.
Finally all those items can be found on one store with no need running here and there. Also Internet can lead you on those (e.g. ebay, amazon, banggood, etc)
HAVE FUN!