I take it you are talking about contrast filters for B&W printing.
Any old set will vary the contrast but the steps won't be even unless the filters match the paper. Ilford sets go with Ilford paper and Varycon sets go with Efke paper (and probably the other East European papers).
If you are taking pictures with a Holga I don't think it matters much the condition of the printing filters.
Perfectly good sets are available on ebay. Or you can 'invest' more money for a new set of Ilfords.