Hard to say for sure without seeing the animals. If they are bred back, the calves must weigh 300 lbs, more or less and be worth 1.50 per pound so that is 450 dollars on the calves. The 3 year old first period longhorns will be worth 450 each. So if they are good, calf raising cows, the pairs will split out to 900 dollars each. If you can buy them for 750-800 per pair, I would buy them. The cows will need to be bred to a Charlois bull to get the best growing and selling calves from them. I have bought a lot of cheap longhorn cows and they make great mothers and raise good selling charlois cross calves and they are not picky eaters. If the cows are small and do not give enough milk, the cows are worth 350 and the calves 350, so 700 dollars is enough for them and you dont want them if they are that type. How much is the guy asking for the pairs?