Cheap SAS Nas or SAS extension enclosure?

[Enquiries]

Hi, I bought 8 SAS hard drives WD HC550 18TB, I need a cheap NAS or a Qnap extension enclosure for them (currently i have 5 nas Qnap TS-832x with 16gb ram).
I beleive I should buy a SAS extension card and a sas enclosure like TL-R1220Sep-RP, no? is it compatible with my nas? or is there anything less expensive?
I dont need extra functionalities, just be able to use RAID and a fast connection, I got everything under 10gb network.
Thanks for your support

[ed]

Here is a list of Qnap supported expansion boxes. You can create a separate RAID and volume and connect it to your existing 832X NAS.Supported Expansion Enclosure for TS-832XModel NameForm FactorInterfaceMaximum Connected NumberNoteTL-D1600STowerSATA 6Gb/s (SFF-8088)1TL-D400STowerSATA 6Gb/s (SFF-8088)1TL-D800CTowerUSB 3.2 Gen 2 (Type-C)1TL-D800STowerSATA 6Gb/s (SFF-8088)1TL-R1200C-RPRackmountUSB 3.2 Gen 2 (Type-C)1TL-R1200S-RPRackmountSATA 6Gb/s (SFF-8088)1TL-R400SRackmountSATA 6Gb/s (SFF-8088)1TR-002TowerUSB 3.2 Gen 2 (Type-C)2TR-004TowerUSB 3.2 Gen 1 (Type-C)2TR-004URackmountUSB 3.2 Gen 1 (Type-C)2UX-500PTowerUSB 3.2 Gen 1 (Type-B)2UX-800PTowerUSB 3.2 Gen 1 (Type-B)2I hope this helps.