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..
Everything, as usual, depends on the context, and in your question we unfortunately don't have one. According to it, this idiom can serve as an attribute like обычный, ничем не примечательный, заурядный or express quantity, as in каких много, навалом, завались, пятачок пучок, пруд пруди.