I’ve gathered some app deals that I found. Some of them going to up to -80% off the price. It’s worth taking a look if you are an iPad user.
ProtoSketch $8.99 > $3.99 (60% OFF)
Desktop-class vector graphics editor. Supercharged with icons, fonts, ui elements, basic and complex drag and drop shapes. It is easy to create anything from logo and icon to web and mobile design. 
Grafio $7.99 > $2.99 (60% OFF)
Powerful diagramming editor. Allows you to create concept maps, flowcharts, mind maps and any other diagrams real quick.
Pixelmator $4.99 > 1.99 (60% OFF)
Full-featured, layer-based image editor that lets you touch up and enhance images, sketch and paint.
Vidra – $4.99 > $2.99 (40% OFF)
Storytelling platform perfect for sharing ideas and making a pitch. Start-ups love this app because in 5 minutes you can upload your idea to youtube as a animated explainer video.
iThoughts $11.99 > $5.99 (50%OFF)
Classic mindmapping tool (fixed layout).Mindmapping enables you to visually organise your thoughts, ideas and information.
Noteshelf $7.99 > $3.99 (50% OFF)
Take notes, annotate PDFs, record audio, draw shapes, sketch ideas, sign contracts, fill forms, print documents.
Graphic $8.99 > $3.99 (60% OFF)
Until recently iDraw – Graphic is a Full-featured graphic design and illustration application for iPad.CV
Carbo $7.99 > $3.99 (50% OFF)
Scans a photo of your handwriting or sketches. And keeps them in raster format.
Some of the deals will probably be available till Cyber Monday. If you are aware of other sweet app deals for designers please post them in the comments and I will update this list as soon as possible.