The best way to find that information is to go to Gunbroker, completed auctions, and look at similar items.
This may save you some research time. I extracted these 16 completed auction prices from about 1,800 BHP prices I've collected over seven years or so. All except the first price are from Gunbroker. The first one is from Smith & Wesson forum classified. Ten round magazines not mentioned but Mec-Gar sells the 10- and 13- round blued ones for $31.10. BHP prices bounced up when the model was discontinued, so if you have 'mint' one, I'd guess its worth to be better than average. Only one way to find out. 11/24/2014. $950. Browning HP Capitan '05 vintage high polish blue example in excellent condition with light handling marks. Pistol wearing good looking aftermarket grips with 2-13 rd mags, matching box, master lock, and paperwork. $950. 01/04/2018. $1,801. BROWNING HI-POWER GP CAPITAN BOXED Complete 9mm Slotted BACK Strap For STOCK EXTREMELY RARE HP 9MM. 01/22/2018. $985. Browning Hi-Power Capitan 9mm LIKE NEW IN CASE. 01/30/2018. $1,500. BROWNING HI-POWER CAPITAN PISTOL W/ TANGENT SIGHT. 03/09/2018. $1,000. Rare Browning Hi-Power Capitan Tangent Slotted 511. 08/02/2018. $1,449. Browning Hi Power Tangent Capitan 9mm Browning Hi Power Tangent Capitan 9mm. 08/03/2018. $1,695. Browning Hi Power Capitan 9mm (PR39292) Browning Hi Power Capitan 9mm (PR39292). 08/04/2018. $1,395. Browning Hi Power Tangent Capitan 9mm LNIB Browning Hi Power Tangent Capitan 9mm LNIB. 08/21/2018. $1,800. Browning High Power Capitan Boxed Browning High Power Capitan Boxed. 08/21/2018. $1,430. RARE Browning Hi Power 9mm CAPITAN BOXED COMPLETE Belgium Tangent Sight. 08/26/2018. $1,304. PENNY! BROWNING HI-POWER TANGENT CAPITAN 9MM LNIB!. 09/03/2018. $1,675. RARE Browning Hi Power 9mm CAPITAN BOXED COMPLETE Belgium Tangent Sight. 09/15/2018. $1,888. Browning Hi-Power Capitan Tangent Slot MFG.Belgium. 09/18/2018. $1,095. Browning Hi-Power 9mm Capitan MKIII 2003 Ser NICE Browning Hi-Power 9mm Capitan MKIII 2003 Ser NICE. 09/24/2018. $1,352. Browning Hi-Power 9mm Capitan MKIII 2003 Ser NICE Browning Hi-Power 9mm Capitan MKIII 2003 Ser NICE. 07/21/2019. $2,000. FN Browning Hi Power 511 SLOTTED CAPITAN LNIB.. ________________ Average $1,457
I too have a Capitan ( no El) model Hi Power but I am in a different situation as I have no desire to sell any of the several hundred firearms accumulated through the years. However the Capitan was a unique pistol that popped up through the years after the tangent sight had been discontinued. Further complications as some were marked FN and some Browning, some slotted and some did not have the stock slot cut into the frame at all. I am fortunate to also have an original 1935 issue to the Belgian army to compare the Capitan with. The
