My best purchase was also the best value - a Fatip Piccolo I won at auction with a Mühle brush for about $15 equivalent. I was a bit nervous because it was my first time with an open comb and I'd read a lot about how aggressive it was supposed to be. I knew from the first stroke that I'd found The One.
My recent favorite shaving purchase were 3 Gillette Adjustable razors, all for $12 at a Thrift Store, Fatboy, Slim and Super Adjustable (Black Beauty) in very good condition. Bottom three of picture. Other than that, it is my Weber PH with Classic Handle.
The single biggest game changer for me was discovering Godrej Red. Less than a buck a tube in Dubai, where I first purchased it. Slickest lather imaginable, and softens whiskers phenomenally if you give it a chance. This stuff improved every shave, not just my straight shaves. Beats the pants off Proraso, good as it is, or any soap. Superlather made from Godrej Red on VDH is heavenly. I try to always stock up when I am in the middle east rather than paying $5 a tube online.
1.) A Maggard MR11/V3A - a gift rather than a purchase. Looks aggressive as can be, but very smooth on the face, especially with a Derby Extra or a 7 O'Clock SS.
2.) A post-war 1940's Ball End Tech. Super mild, bu efficient. Pairs beautifully with a Feather.