Megillah 27a - Selling an Aron and Buying and Aron

If one already sold an Aron (bidieved), can they use the money to buy another one, or must they go up in the level of Kedusha?

The gemara concludes that although one may not be allowed to sell a Torah to purchase another Torah (even a newer one), if it was already sold one should use the money to purchase another sefer Torah. Rashi explains that bidieved we tell you to use the money for another sefer Torah because "if not, what will you buy with that money". The Pri Megadim (O.C. -M.Z. 153:1) points out that based on Rashi's sevara, this only applies to a sefer Torah where you can't possibly go higher. But, if one sold another tashmish kedusha like an Aron or Paroches, since you can go higher, even bidieved (after it was already sold) we require you to use the money for something that has a higher level of kedusha.