When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It merely makes the task take one less step. I just take a prybar and release all the tension by prying the tensioner as far to the passenger's side as it will go, then I tighten the hold down bolt. Install the belt, hold the crank still with an appropriate sized socket and breaker bar, then release the tensioner onto the belt. Rotate the engine by hand (helps to take the plugs out on one side) a few revs, check the timing, then tighten both bolts. With the tool, you can hold the tensioner to the side with the belt in place already. If the timing cover isn't in place, I can swap a timing belt on a Lima in less than 15 minutes now. I left it off on my SVO...but then again I went to the trouble of painting the tensioner and auxillary shaft sprocket and I have a billet aluminium cam sprocket. No sense in covering up all the shiny parts!
FWIW, I've only seen the tool on eBay a couple of times as part of the 2.3L service tools kit. Many times when that tool kit is available the belt tool is missing, no doubt kept by whomever used the kit last. I wouldn't go out of my way to find the tool. If you can't find it in a casual search, then just get a prybar.