The guy in Vineland with the snow blower and decks on CL had a bunch of wheel weights, I'm not sure if they were Bolens or not but he had pile of them there. He had a ton of plastic weights in his truck the day I was there. Nearly all were 8" weights.
Can't you just fill the front wheels and hang some weight? I don't think I like the idea of having to deal with wheel weights everytime I have to set the tire pressure or pack the front bearings.
Weight is weight, I don't think I'd hold out for Bolens branded weights if I needed the machine now, what you need will no doubt turn up sooner or later. Depending on what front wheels you have, many other brand weights will work just fine, maybe even better.
I've seriously thought about casting my own weights out of lead, but the added weight would be far more than cast iron.
Something to think about too, the farther forward you mount weight to counterweight a rear attachment, the more effective it is. A simple bar mounted out front with the same 100lbs you would put on the wheels will counter balance a good deal more with the same weight. Most big tractors use either suitcase weights up front or a central ballast bar just ahead of the axle. My Case loader at work has a 500lb cast iron weight just under the radiator to counter balance the back hoe. There would be no way to put that kind of ballast in or on the front wheels, nor would it be as effective.