I am in process of searching a few cycads to purchase. I have an opportunity of getting a few more rare ones. Should I choose maybe 2 a bit bigger (caudex 2.75-3.5") or 3-4 smaller (up to 2")? They are not cheap, that's why I have to stay to smaller sizes and I'm not asking about caudex sizes 5-6" or more. On the other hand, maybe if I choose bigger one/s, would they be more resistant? I could buy a 4" one with all the money I have put aside for all of them, but I also like the other specimens, that's why I was thinking about choosing at least 2 of them, different species.
I know, I am so undecided... I am afraid I will end up buying only a Sago from Home Depot...

It's almost impossible for someone else to make this decision for you. How much experience do you have with growing Cycads? If plenty, I would say buy more different small ones; if not so much, maybe better to go with just one.
And

Hi! Are they fully hardy where you are? You may be talking about potted plants from those small sizes, but I think you mean for them to be in the ground? They come back to life here, but usually look ugly for a few months from frost bite/defoliation. I've lived here 6 years and none of the Cycads nearby look noticeably bigger than they did then. The foliage does not look like it would decompose in a compost pile over winter, at least not the petioles. I would choose a palm here instead because of these things. Hopefully these are not issues in your zone.

If there are significant price differences just because plants are an inch or two larger, it's probably because they grow so slow, but I'm not familiar with these except driving by some often.