I don’t know about a Volvo but you can use a SAAB, info and links below.
http://www.tigersport.pwp.blueyonder.co.uk/mk3supras/main_frame.htm
Click on modifications (left side of page) and then scroll down to SAAB Blow of Valve
http://www.supras.co.uk/resources/MkIII/tips/bov/bov.htm
BOV Valve (Bosch part No 280 142 110) SAAB part No 44418 This valve is used on a 1996 SAAB 9000 Turbo. GB Price ?32:77 incl. vat. about $65.54 US
Not sure if you can get these ones in the US, but this company does a shiny bling one.
http://www.partsforsaabs.com/product_info.php?products_id=2281