In this area, right now weaned heifers in the 5 wts are bringing 1.25 to 1.40. So a heifer is worth in the neighborhood 650 give or take. Bred cows are in the range of 650 to 1250 with a few bringing a bit more. The cheaper ones are usually older cows, but we buy some that are in good flesh because if they raise their calf then we will make a little bit when we turn them over. Bought a nice charl 3rd calf, with a decent heifer calf by her side for 850. Breds and cow/calf pairs are cheaper now so it makes more sense to sell the heifers and buy a couple of breds or c/c pairs. But, we have been doing this for awhile and know the risks and are willing to take some with old cows.
We do raise some of our better heifers up for replacements because we know what the dams are and like the bulls they are out of. They often make our better cows and we do also cull for disposition.
Starting out we bought what we could afford, culled what didn't do good, culled what was a nut case or fence jumper. We would buy cows that weren't the greatest, get a calf, make a few dollars and try to buy better the next time. Got soaked a few times and hit a few good ones. Except for 2 times, we have never borrowed to buy cows. We bought 40 and financed them for 2 years. Have some decendents now from them and several are out of the same cows or their first daughters. Most were sold after a few calves. Then we borrowed to buy 75 from a family friend who was dying of cancer and paid them off in 3 years. It was a favor, and gave his wife some consistent income and they were getting some age and we bought them right. As a rule we do n ot borrow to buy. If we were getting into purebreds, show cattle or something, maybe. But the markets are down a bit and it doesn't make sense. 3 heifer calves will buy 2-3 decent bred cows easy right now. A potential for nearly doubling your numbers.
In the beginning we bought the best bull we could afford which wasn't much. Then we would sell him after 1 or 2 years, and buy a better one. Now we mostly buy registered, but not always, so that we know the breeding/bloodlines behind him. Have bought a couple from friends who were going to change bulls and we liked the calves from their present bull. The good thing about that is we could buy him for cull price or a little above, and still get a good bull. Helped to have some neighbors that we could work with. I do some AI and we have raised up a bull or two from that. But it is easier to buy one that is ready to breed. I would think that AI would be your best way to go if you have a chute to catch up the cows, and you won't have to feed a bull for 12 months when you only need him for 2 months. For only 2-5 cows, or even 10 cows it is not economical to own a bull. If you have any neighbors that you could ask if they are going to change bulls and maybe you could buy theirs for pound price that they would get at the stockyard, then use him and sell him in a couple months for about what you have in him. That way you wouldn't have to keep him but for a few months and not have a ton of money in him.
It is true that a bull is half of your calves, and you want calves that are better than their mommas, so that they sell good. So a good decent bull is the smartest way to go.