Collecting vinyl has never been hotter than it is right now. And with more people getting into rare vinyl, the higher the prices keep going. The most valuable records are still mainly from the 60s and 70s, but it won’t be long before vinyl from the 80s and 90s starts exploding in value. The best time to start with those records is right now. Promo releases–stuff that was released to the industry but never sold to the general public–is what you want.
For example, if you can find this collection of material from U2's movie, Rattle and Hum, you’ve got something pretty cool. It’s a single, CD, LP and cassette all stored in a special flight case. If you ever run across such an animal, it might be worth the investment. The current valuation is just over $2K Canadian.
More on the topic here.