A few years ago we bought a few “Sous Vide” on eBay. They sit in a tray and hold the temperature well, especially model SV228, which may no longer be available.
We bought the size 14 one from the link below.
https://metappaustralia.com.au/products.php?cat_id=7&subcat_id=65
I bought mine of Alixpress about 2 years ago, so much cheaper and I have had no issues with them at all. I got the small one and it holds about 10 test tubes or 4 250mL beakers, perfect for individual groups with different requirements. Just watch the shipping costs some vendors do free shipping others charge a lot. (Brand HH-1)
https://www.aliexpress.com/item/4001358444855.html?spm=a2g0o.productlist.main.33.6a6d418e0CUd7J&algo_pvid=5099a473-b7d4-4124-87b9-88eaccb5d501&algo_exp_id=5099a473-b7d4-4124-87b9-88eaccb5d501-16&pdp_npi=4%40dis%21AUD%21365.87%21274.39%21%21%21231.30%21%21%40210318bb16946528088304255e5fc2%2112000018000577789%21sea%21AU%211860169683%21S&curPageLogUid=59UnEmSvERPZ