I was looking up "a dime a dozen" in Russian and the closest equivalent I found was "обычная шпана" on Reverso, but I'm pretty sure this was just a literal translation. The English meaning of "a dime a dozen", according to Oxford Languages, is "very common and of no particular value." Is there a more natural way of saying this in Russian?
"обычная шпана" is totally unrelated, although it may be a suitable translation in some context.
However, have your pick: http://www.synonymizer.ru/index.php?sword=%F5%EE%F2%FC%20%E6%EE%EF%EE%E9%20%E5%F8%FC
The titular expression is quite rude, but I can't at the moment choose an expression that has the exact same meaning.
Perhaps, как собак (нерезаных) or воз (вагон) и маленькая тележка.
This one ГРОШ ЦЕНА В БАЗАРНЫЙ ДЕНЬ is also related to money and has a close meaning. But I think it's less common than the English phrase. Besides, it conveys the aspect of worthlessness, but not the commonness.
I don't often post answers to questions about Russian because I'm not a native Russian speaker and don't presume to teach anyone Russian. But I have a Russian friend living in Miami and working as a translator, and I once asked her to translate this very phrase for me for a forum I was chatting in. This was her version:
In South Florida, Spanish interpreters are a dime a dozen, so you really have to stand out if you want to get noticed and excel in this field.
В Южной Флориде переводчиков, работающих с испанским языком, полно/пруд пруди/как грязи. Поэтому для того, чтобы тебя заметили и ты смог преуспеть, надо очень сильно отличиться..