Format cells based on 2 separate cell data, incorporated into the format

My Title makes no sense, i know.

I am trying to generate a reference number.
The reference number is generated based on a few factors..
In this case the reference number ALWAYS starts out the same
REF#06-RT1000
It is the next series of numbers that is extremely important and are based off of data (the price) entered into another cell.
This is easy, as I can format my column to auto populate my reference number and use a formula to add the price in at the end so that if the price were "6.99" my reference number would look like:
REF#06-RT1000699
HOWEVER, sometimes we have special pricing and I need to incorporate the 2 amounts...
I am struggling to find a way to incorporate that into my format & formula
So if the price is 6.99 but i have special pricing of 4.99 my reference number needs to look like:
REF#06-RT1000699SPC499

so I have seperate cells with the different prices but it becomes difficult and poses threat for error if I need to manually add this soecial pricing to the end of my refernece number./

I have attached a spreadsheet to show what i mean.

THanks.

This is pretty much what I am looking for, and your assumptions are accurate, however, is there a way to differentiate between the 2 prices? Typically my reference numbers, when there is special pricing, look like this: REF#06-RT100307SP175. The SP tells my sales department that there is Special Pricing available on that product. If it is not possible to incorporate the "SP" into the reference number, is there another option? Maybe "." or ":".. just something to separate the 2 numbers.
Thank you so much!

thank you this was most helpful