Something Diffferent

It's not a substitution cipher is what you said, else I'd have started off with 74 represents T, 100 represents H, and 91 represents E. and continue cracking it that way but it's not a substitution cipher like you said.
I'll leave a hint for others to figure it out.
ABCDE
FGHIK
LMNOP
QRSTU
VWXYZ
No J, makes it easy to do a 5x5 square.

So that may well be the key - a re-ordering of the letters (and then some kind of numeric substitution).
There's insufficient information here to allow a decipherment unless (A) there's a lot more than $20 at stake, or (B) it's a straight monoalphabetic substitution or perhaps a Vigenere, or (C) there's more information available.

Guess we'll be needing more hintinosity from you, I'm missing something the others must have been notified about before you posted this.

You aren't even close in your guess of the method, sorry :)

The others haven't been notified of anything that isn't in this post, nor do they have information relating to it. Long ago, I revealed this code to bjkrz, so I just put the disclaimer up there to keep him off of this particular puzzle. For all I know, he may have forgotten all about it.

Here are some more hints, since you requested them. The omission of the J is not arbitrary. There is literally no possible way to represent the letter J in this cypher. None. Zero.

You may note that the digits in the cypher range between 1 and 99. Here is another hint: the highest possible number in this code is 110.

So the question you have to ask yourself is: What number system goes up to 110, and cannot possibly represent the letter J?

Here's another hint: this has little to nothing to do with mathematics.

Also, if it is your wont, you have my permission to attempt to crack this with a computer. I'm curious to see if it would work.

And hey, thanks for taking interest in this little community :)

Firstly you had a lot of typos in that but got it figured out since they were simple words.
you have to get your periodic table of the elements, the numbers are element numbers. Basically you write the symbols

you have to get your periodic table of the elements, which is the key.
the first word 74+26-9

Eg. element 74 is tungsten, symbol W,
element 26 is iron symbol Fe, then you subtract element 9, which is fluorine, symbol f so you're left with "we".

Well that should get the whole message. lazy but do I win?! :)

AND the reason there's no j, is because there's no j on the periodic table!
there's no j on the table, hence it can't be encoded

Solution:

w+e C+a+n+t s+o+L+v+e pr+o+b+L+e+m+s b+y u+si+n+g t+h+e s+am+e etc....

Good job. . .I'm guessing my hints made that abundantly clear?