Boomboxes/ghetto blasters used to be a ubiquitous piece of equipment in the language school classroom, especially in organisations where no custom built language lab was available.
Now largely replaced by play-only CD & DVD players, they don't usually have a slot for recordable cassettes, although boom boxes manufactured during the transitional phase from tape cassettes to CD/DVD often had both and there might still be some dual-function models beiing produced.
Nowadays, a miniature digital voice recorder or the built-in recorder software and integral microphone in your laptop will do the trick, especially if you connect it to a pair of larger external speakers.
IMHO, giving students the opportunity to hear their own voices is essential. What they believe they are saying is usually very different when compared with the original pronunciation recording of a native speaker! OK for one-to-one classes or very small groups, but rather impracticable in developing countries with up to 60 students crammed into an echoing concrete classroom.