Plastic Practice Solid Golf Balls

Comment: Ever since I cracked or dented my old Wilson white plastic solid practice balls, which are no longer available (I gather), I've been looking carefully for a substitute. Other balls I've bought at Kmart and Walmart were all cheap and lightweight. These balls are not much different. Yesterday, I used, for the first time, the 4 dozen I bought, and, at first, I thought they were fine. They popped off my 9-iron (not as well as the Wilsons, but OK for my purposes) and took spin that told me what I wanted to know about each swing. Starting after the second bucket, I noticed that a couple of the balls were already dented, and soon I heard a hollow sound with a couple of balls that told me the balls were cracked. By now, the second day, I'm down to 40 balls, and this is just hitting easy with a 9-iron, a disappointing outcome. Where are some good solid white plastic practice balls? The rubber ones I use, the Callaway Soft-FliteCallaway Golf HX Soft-Flite Practice Ball - 18-Piece - C10316 and the Almost Golf P3 Almost Golf Practice Ball 36 Pack balls are fantastic, but at this time of year (in the Northeast), my backyard is too soft to hit them there and then go pick them up wearing my Sorrel boots, which leave deep footprints in the thawing ground. With the plastic ones, I can hit them into my driveway, and no harm is done. However, the way things are going, these will be history in 5 more days at the rate they're failing now.