I've said it before, and I'll say it again: Crucial is not a particularly good, or cheap source for memory. Because of the way they set up their configurator, you can end up paying more for ram that is for a specific machine, than for that same type of ram, listed by type. I would generally go through the supplier we use at work (CEC), but failing that, cheap generic ram is pretty easy to find. With your machine, the memory is going to be older, which means that it will cost more to buy new. Memory is a commodity market. The prices fluctuate based on supply, and supply is based upon demand. So, in an age like this one, far less people have a demand for the older types of ram you will need, and as such, less of it will be produced. So, that which is produced is offered at a higher rate. Wholesalers (such as Crucial) are stuck with this floating rate. End user retailers who stock memory have bought it at some particular price, and have either marked it to current market value (Big box retailers), or have marked it up with a standard margin based on the memory's specific cost (Most smaller retailers).
My point is that if you can find a smaller retailer who brought in some of the ram you need some time ago, and has it marked up from its cost, rather than to market value, you will get it much cheaper than Crucial, or other such wholesalers will sell it for.
But, as I said, you can literally tell me the specific type of machine, and processor speed, and I can tell you the memory you need. I could even tell you the CEC part number for it. My memory configuration skills are kinda creepy with regard to G3 and up Macs.