I'm wondering if theirs money in throwing in a few young heifers when I buy and then sell them private as replacements?
Yes and no.
Money can be made if they live and turn out to be quality looking animals as buying at action does carry a risk factor.
Then there are still the unknowns that will bring down your sale price for replacements.
I don't think you will gain any profit selling them as replacements heifer vs beef.
It has been my experience that bought heifers do not make good dollar salable replacement heifers because of all of the unknowns.
Example:
I recently purchased 6 replacement heifers that were destined for Athens from my neighbor who runs a commercial heard.
I paid him the high price for each of their weight class for that weeks market at Athens.
This saved him trucking and commission fees by me buying at the farm.
And also any weight loss due to stress.
Now why would I pay him a premium price for these heifers?
Because I already know:
he runs a closed herd
his heifers almost always bring the high price at the sale barn
I know and can see his cows and bulls
I know how they are well care for
I know what they are feed
I had the time to look them over carefully
In short I know every thing about these heifers as if they were my own.
There were no unknown for me at the time of purchase.
Now had these very same heifers gone to action and I didn't know all of the above and didn't know they were my neighbors animals by the NT tag, I would have only bid about 25% less then what I paid for them and most likely not been able to purchase them, as other buyers who know the seller by the code of the NT tag would have surly out bid me.
Hope this helps
Liz