Don't forget that you can get oversized saucers in order to catch significant runoff. My 3gal containers will sit in a 10" saucer. But, by the time I reduce my crop to 4-5 females to flower I use 12-14" saucers to catch more runoff (margin of safety).
Lowes sells a deep-wall saucer. It's flimsy clear plastic. I keep some of those for when I know I'll water for large runoff (semi-flush).
Botanicare sells an "OD" tray which is sized with an "outside dimension" to fit in popular tent sizes. I have the 4x4. Got it for $120 from the local hydro store. I sit it on top of 6" square cinder blocks (Lowes) that are shimmed with cardboard to get a slight forward tilt. The 6" lift allows me to put a Sterlite shoebox (or slightly larger) container under the drain hole to catch runoff.
Makes watering much easier. But, if you want to measure runoff's ph it's not as good. You'd still need to insert a saucer to catch runoff. But, this "OD" tray thing is great. (You can also get by with the less-expensive 3x3 hydro tray (not an "OD" size, so it's slightly larger than 3x3). In reality, we keep our containers a few inches from the tent wall, so a 3x3 tray would probably be enough to hold the containers (with 5" of open space all the way around).