The purchase price of large industrial pressure vessels (see e.g. picture: https://www.cymisa.com/areas-de-negocio/industria/parques-almacenamiento-combustible/), can certainly only be found out in consultation with manufacturers. The sphere drawn in the picture below has a volume of 24,500 m³. If we assume that the sphere can withstand a pressure of 150 bar, then W komp = 12412312500 Joule = 3448 kWh
If we want to achieve a storage price of 100 €/kWh, the entire plant (pressure vessel plus compressor plus reconversion = air motor) must not exceed a price of 345,000 Euros. Exact prices would certainly have to be determined in discussions with manufacturers of compressed air tanks (plant engineering). In any case, the order of magnitude of the price sounds realistic.
By the way, high-pressure vessels with a pressure resistance of up to many thousands of bar can be found at: https://www.dustec.de/de/produkte/druckbehaelter.html?gclid=EAIaIQobChMIkKnEhJ_l8AIVzeh3Ch3ugQkPEAAYAiAAEgIS2_D_BwE
It has been known for many years that compressed air tanks are even used experimentally in the mobile sector (for cars and for locomotives): https://de.wikipedia.org/wiki/Druckluftauto