You shouldn't have to spend more than $5 for a full weekend of gaming between Steam's free access to Dead Island: Riptide, The Binding of Isaac for $0.99, assorted $5 specials at Get Games and a new Humble Mobile Bundle with six Android games for four bucks and change. Also of note, GamersGate has Mass Effect 3 Digital Deluxe for only $7.49 as well as every Telltale release for $37.50, while Green Man Gaming has solid prices on the Batman Arkham and Lego titles.

Steam
58 Dead Island: Riptide $13.59 (66% off + free weekend)
74 Dead Island GotY $4.99 (75% off)
79 Street Fighter X Tekken $10.20 (66% off)
79 Street Fighter X Tekken Complete Pack $20.39 (66% off)
77 The Secret World $14.99 (50% off)
84  Red Orchestra Franchise Pack $14.99 (75% off)
77  Tripwire Interactive Bundle $24.99 (75% off)
82  The Binding of Isaac $0.99 (80% off)
Septerra Core $2.49 (50% off)
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Amazon Digital
78 Scribblenauts Unlimited $5.99 (70% off)
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GameStop
82  Darksiders $4.99 (75% off)
78 Darksiders II $12.49 (75% off)
83 Alan Wake Collector's Edition $8.74 (75% off)
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GamersGate
87 Mass Effect 3 Digital Deluxe $7.49 (75% off)
87 Mass Effect Trilogy $19.98 (50% off)
60 StarDrive $14.98 (50% off)
71 Nuclear Dawn $2.50 (75% off)
88  Telltale Complete Pack $37.50 (75% off)
Wastelands Strategic Bundle $12.49 (75% off)
Darkness Within Collector's Edition $3.75 (75% off)
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GameFly
86 C&C: The Ultimate Collection $9.99 (50% off)
82 Jade Empire Special Edition $4.99 (67% off)
87 Burnout Paradise: The Ultimate Box $4.99 (50% off)
86 FIFA Soccer 13 $11.99 (40% off)
81 Kingdoms of Amalur: Reckoning $9.99 (50% off)
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Green Man Gaming
88 Borderlands 2 $13.19 (67% off)
52 Omerta - City of Gangsters $9.99 (75% off)
79 Wargame European Escalation $6.79 (66% off)
45 Confrontation $4.99 (75% off)
90 Batman: Arkham City GotY $7.49 (75% off)
90 Batman: Arkham Asylum GotY $4.99 (75% off)
84 Lego Batman $4.99 (75% off)
82 Lego Batman 2 $7.49 (75% off)
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Get Games
77 The Darkness II $5.00 (83% off)
87 Civilization V $5.00 (83% off)
73 Spec Ops: The Line $5.00 (83% off)
75 Serious Sam 3: BFE $5.00 (87% off)
92 BioShock Infinite $19.99 (50% off)
90 Company of Heroes Complete Pack $7.49 (75% off)
79 R.U.S.E. $5.00 (50% off)
68 Kane and Lynch 2: Dog Days $5.00 (50% off)
82 Hotline Miami $5.00 (49% off)
46 Call of Juarez 3: The Cartel $5.00 (75% off)
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GOG
Up to 80% off a group of five titles including VVVVVV
60% off select strategy titles