Honestly, you are almost better off to simply buy wheel weights already in ingots for $1/lb. I've yet to find a decent source for "soft" lead, and have only been able to find wheel weights at tire shops....but even that is unreliable. A few months ago, I hit 6 different shops and ended up with ZERO....they are all scrapping or selling to someone else. One of the local salvage yards will sell you all the wheel weights you want...for $0.65-75/lb or more.
I am in the same boat as you, I got the itch to start casting several months back and have been trying to stockpile a bit of lead. I was able to get a few buckets of wheel weights, but still need to sort them and separate the steel/zinc weights from the actual lead stuff....and then have to sort through and separate the clip on and stick on wheel weights. Looking at a 5-gallon bucket, this will be extremely time consuming, which is probably why I haven't done it. Once that is done, you still have to smelt it, flux it with sawdust, and pour into ingots. Watch a few Youtube videos, there is nothing quick abut the process....and add to the fact its dirty, hot to do in the summer, and very unhealthy if not done correctly, buying is a much better option. Hell, I can tell you that there is no way I could sell it for $1/lb, I'd have way too much time and money tied up into that pound to just sell for a buck.
My advice? Buy 30-50lbs of wheel weight in ingots, and they try finding/hoarding wheel weights. Use the ingots to go ahead an pour some bullets, and see if that is your thing. I can tell you this, up front costs (especially for good molds) is high, and you have to shoot a lot to recoup/save any money.
Just to be curious, what cartridges are you wanting to cast for?