You have seen this before. If you speak (and read) english. My numerals were not numbers, they were spoken words. In the english language, an apostrophe stands for unspoken words.
One million, three-hundred thousand, fifteen dollars, is written as $1'300'015 because the first apostrophe stands for the word "million" and the second stands for the word "thousand".
To be clear, the apostrophe can stand for individual letters (e.g. the "o" that is not in "don't") or even for multiple words, (e.g. "n the" removed from 4 o'clock).
Your comma, as in $1,000 is erroneous within any international forum as it is a decimal indicator in most french-speaking languages -- as in $2,99 for two dollars and ninety-nine cents. Obviously a period is equally erroneous in the reverse scenario. Of course, a space is ambiguous where one number may be seen as a list.
So, as usual, where there is no formally enforced formatting structure (as is the case across international boundaries, such as this one) especially across disciplines (such as this one), and especially wherein the very nature of the discourse varies from moment to moment (again, such as this one), written language must always serve its most essential role -- to document the spoken word: speech.
When spoken, such as these conversations would be if they were done in-person, "$1'000.00" would be spoken aloud as "one thousand dollars and zero cents". As such, the apostrophe is required, in order to replace the spoken word "thousand".
If, on the other hand, you were to speak "one three zeroes dollars", then you might transcribe that as "$1,000". Perhaps "$1.000" would be transcribed as "one point zeros". I'm not really sure.
So, in short, you absolutely have seen the apostrophe used before, and I am using it in precisely that manner, and for that very same purpose.
Also, in short, as a discussion forum, we utilize the written word as a mere transcription of the spoken word, for in the absense of any agreed-upon formal structure, numbers would have no direct meaning (just as numbers alone never do). As such, these transcriptions are merely a substitute for spoken word, and as spoken word, the apostrophe is the only correct punctuation.
Alternatively, of course, one could transcribe "$1'000" as 1 thousand dollars, though that would be as obscene, perhaps as $1 thousand, for obvious reasons.
Interestingly, as is obvious from my initial discourse, my use of numbers was purely conversational, as not a single one related to anything, and hence could have been replaced with any other number of similar magnitude.