It is highly unlikely that you will be able to find them anywhere. Too many sellers claim that their bulk lots are unsearched, but they are liars. Somewhere along the line, someone has searched them. About the only way you will be able to find Wheaties unsearched is to buy original Mint bags, and that won't be cheap. Even then, you will need to examine the stitching very carefully with a loupe to ensure that the bag has not been opened and re-stitched. Chris
99.99% are searched, but there are some collectors who literally have hoarded the wheat cents without looking at them. However, no one will tell you such sources once they find one, as they enjoy that relationship. Hopefully you belong to a club where someone may be reaching their later years and want to pass them on as such. they usually got them as a "poorman's savings plan" by buying a bag from the bank every month or 3 months, 30-50 years ago or more. Rural areas were more into this before IRAs, etc. If you find a coin club with old timers in their 70-90s, be kind, talk to them and ask in the meeting if anyone has old groups of cents they aren't needing. Estate sales also may be interesting. Avoid Ebay of course.
You don't want to buy any "unsearched" wheat pennies online unless you're interested in hoarding as many 1956-D, 1957-D and 1958-D cents as possible!
Congrats on the BIG 70! I agree with Chris and the others. Very slim chances of finding anything unsearched. Especially online. On the other hand (and I've said this many times), what you are looking for, may not be what the guy who dumped them off at the bank was looking for. I've never seen a mint bag of wheat pennies in person. If I would ever come across that, I would hop on that opportunity!!!
