I can't answer about Vaja, because I don't have one. So, I cannot answer your question about discounts, or whether Vaja makes hard cases. Re matching cases, buy what you like. My briefcase is beautiful, simple, elegant, tan, soft, hand-crafted, Italian, my MBP is aluminium; both are exquisite versions of their respective forms and function. Both work well. Do they match? I don't care. I bought the briefcase because it is beautiful, and I love beautiful, well-crafted, well-made goods. I bought the MBP because I had become a fan of Apple products for a variety of reasons, wished to switch, and I liked the MBP.
Ask yourself why you want it. If it is beautiful, and you can afford it, yes, it is worth it. If there is something which you actually need (rather than simply want) and need badly, then the money spent on a leather bag might be better spent elsewhere.
If it is well looked after, leather will last for ages. When it rains, dry it, by wiping it off; do not place it anywhere near a source of heat, or it will dry out and harden. Season it regularly - ie a few times a year - with saddle soap, which will protect it from the elements, such as rain.
Cheers and good luck
