I test overshoes for a living and here are eight Black Friday deals I'd buy

Spatz Legalz Glo overshoes:
UK: £69 £45 at Sigma Sports
35% off - The Spatz LegalZ Glo overshoes are the same as the Legalz below but with High Viz printed accents. There's a bigger discount on these overshoes so unless the splash of colour is a deal breaker, these are the top pick. World-Tour riders have helped design the Legalz overshoes. They are also available in all sizes currently. 

Spatz Legalz Pro overshoes:
UK £69 £52 at Sigma Sports
25% off - The Spats Legals Pro are a really great all-round winter overshoe. I wore a pair for much of last winter and have done plenty of wet and cold riding in them. They are slightly lighter in construction than the Roadman and Pro offerings. But unless you're doing really long, bleak rides these are about as good as it gets. Size S and L/XL are available which equate to the following EU sizing: S - 38-42 L/XL - 46-49.

db extreme weather
US: $47 $24.49 at Wiggle
UK: £38 £20 at Wiggle
48% off - I'm currently testing the dhb extreme overshoes and for the money right now they are a good buy. They are a really burly pair of thick neoprene overshoes that will stand you in good stead in a wide range of conditions including rain. All sizes are available and you can check the size guide here. 

Castelli Entranta:
UK: £65 £47 at Sigma Sports
28% off -  I was out testing the Entranta overshoes from Castelli only last night. They are currently only discounted in the UK and are available in S-XXL sizes. They are soft, stylish overshoes with a fleece interior. There's also a wide neoprene cuff at the top of the ankle which I really like. If you want pure wet weather protection look to the Spatz and dhb. But if you want a warm, stylish all-rounder for a bit of everything these are great.

GripGrab Aqua Shield:
US: $65.70 $48.49 at Wiggle
UK: £55.95 £41.99 at Wiggle
26% off - The GripGrab Aqua Shield overshoes are lightweight tall overshoes that are designed to be worn underneath your tights or legwear against the skin. I've seen plenty of people wearing them incorrectly though you can wear them over kit if you want to. They aren't completely waterproof (in my opinion no overshoe is) but give great spray and rain protection and you really do notice how much more comfortable your lower legs and ankles feel with them sitting against your skin in the rain. Sizes S-EU38-39 / M EU40-41 and 3XL-EU 48-49 sizes are available.

Castelli Toe Thingy 2:
US: $24.99 $19.70 at Amazon
UK:  £22 £17 at Amazon
23% off - Toe covers add versatility as well as milder protection when you don't want full overshoe bulk. Toe covers can also go under full overshoes first for freezing days so represent good value. The Toe Thingy 2 covers are rated for 10-18C / 50-64F and are undersally sized.

dhb toe cover:
US: $18 $12 at Wiggle
UK: £15 £10 at Wiggle
33% off - This is another good deal if you want to add to your overshoe collection or gain some extra protection under your overshoes. Both sizes of S/M - EU38-42 and L/XL - EU43-47. For a small amount of money, you can gain spring and autumn protection and the ability to layer under full overshoes in the depth of winter, great value!

Velotoze Tall 2.0 Shoe cover
UK: £18 £6 at Sigma Sports
67% off - This deal is a little more specific but if it's the right fit for you, you are getting an absolute bargain. Size Small (EU 37-40 shoes) Velotoze Tall overshoes in green for Under £7/$7. Velotoze are versatile and aero and provide great wet weather protection. If you like the colour and they are your size, buy a few pairs at this price!