How to Downgrade PS3 Slim to 3.55 using the E3 Flasher (The Easy Way) - YouTube
A pawn shop near me had a new in box PS3 slim! In mint condition. Check it out. Check comment for more info since it seems I can't post pics and description. :
Sony PlayStation 3 PS3 Slim 160GB Console PS3 3.55 (CECH-2503A PS3 Firmware 3.55 | eBay
Original FW 3.55 DYN-001 Motherboard for PS3 Slim Game Console CECH20xxA/B Mainboard - AliExpress
Downgradable PS3 Models - Wololo.net
Sony PlayStation 3 60GB PS3 60GB CECHC03 FIRMWARE 3.55 (FW 3.55) Plays PS2/SACD 711719699750 | eBay
1000GB New White case PS3 Slim 3.55 Sony PlayStation 3 Fast Shipping Clean PSN | #1789585242
How to install PlayStation 3 custom firmware, run homebrew - AfterDawn
Playstation 3 Slim 3.55 for Sale in Westbury, NY - OfferUp