Check out the 2nd link from post #11 above. ~$50.
It's bi directional. Will accept 3.5mm minijack, unbalanced RCA phono or unbalanced 1/4" TS jack. Output to balanced XLR and vice versa.
The first link is cheaper at $25 but not so versatile.
Avoid the very cheapest if possible. They are filters to remove or reduce the noise. You need transformers to 100% guarantee isolation.
Makes sense to buy an audio interface with balanced out when you upgrade. Works like TOSlink to isolate grounds but without the risk to SQ of doing the conversion in two different stages at two different locations without any control or feed back.