Where might I look for known good 50 pin SCSI hard drives?

Computer Type: PC/Desktop
System Manufacturer/Model Number: Custom
OS: Win 7 Pro 64 Bit
CPU: Intel i5-4670K @ 3.4 GHz
Motherboard: Gigabyte GA-Z97X-Gaming 3
Memory: 16 gig
Graphics Card: On board
Hard Drives: SSD C: Drive 2 off 1 gig SATA in software RAID1 as D: Drive
Browser: Firefox
Antivirus: Avast

Computer Type: Laptop
System Manufacturer/Model Number: HP DV6 3225
OS: Windows 7 Home Premium
CPU: Intel(R) Core(TM) i3 CPU 350M @ 2.27GHz Arrandale
Motherboard: Hp 144C v-65.38
Memory: 2x 4096 MB (7880 MB available) DDR3 (PC3=12800)
Graphics Card: Intel HD Brightview intergrated
Hard Drives: WD Black 500 GB Internal 7200 rpm WD Blue 500 GB internal 5400 rpm (Cloned backup) (2) Seagate Backup Plus 4 TB externals (2) WD My Passport Ultra 4 TB external
Browser: Palemoon 29.x.x 32 bit
Antivirus: Avast

Computer Type: PC/Desktop
System Manufacturer/Model Number: Antec desktop; Acer Aspire laptops
OS: Windows 7 Professional 64-bit
CPU: Desktop i5; Acers i5 & i7
Memory: desktop 16GB; 1 Acer 8GB & 1 Acer 16GB
Hard Drives: 1TB split into 2 equal partitions [OS and data] usable by RJS
Internet Speed: AT&T DSL
Browser: FF, GChrome, msIE
Other Info: Windows 7 Firewall, Emsisoft AM/AV, MSE [scan-only], SpywareBlaster, Ruiware/BillP combine

Computer Type: PC/Desktop
System Manufacturer/Model Number: medionl/Aspire 6930G/acer x55a
OS: W7 home premium 32bit/W7HP 64bit/w10 tp insider ring
CPU: E5300 dual core
Motherboard: medion MS7366
Memory: 3gb
Graphics Card: Nvidia Geforce 7100 Nforce 630i
Monitor(s) Displays: avixc
Internet Speed: n (isp resticted to 72)
Browser: palemoon
Antivirus: mse/pands
Other Info: Belkin Fd7050 n USB using Railink RT2870 drivers, more upto date