Beginner at collecting question!

[LiquidShu]

I am just beginning to get into collecting merchandise from my favorite series. I am going to be focusing on High School DxD but really don't know where to start (in terms of item rarity/how valuable it is.) Would you price an item that has already come out but was made in a limited amount (pretty sure that's the way with most collectibles) or an item coming out in the future that is available for pre-order with another figure that you can buy for the set or (last but not least) a game that is unopened with all the limited edition items? If the links will help I will post them. This will be my first item and I am not sure which one would be the best to kick start it 

 

http://www.ebay.com/itm/New-Nintendo-3DS-High-School-DxD-Limited-Edition-import-Japan-F-S-Earphone-Strap-/201089823429?pt=Video_Games_Games&hash=item2ed1e332c5 - Game

 

http://www.amiami.jp/top/detail/detail?gcode=FIGURE-005857 - Bunny Figure Akeno (Pre-Order)

 

http://www.amazon.com/Good-Smile-High-School-DxD/dp/B00IM66FH6/ref=sr_1_1?ie=UTF8&qid=1401751304&sr=8-1&keywords=rias+gremory%3A+bunny+version - Where i would buy the figure; pre-order goes with Bunny Figure Akeno (amiami is sold out) 

 

http://www.amiami.jp/top/detail/detail?gcode=FIGURE-002652&page=top Sold out already released figure, would buy on ebay or amazon. If I did get this one most likely would have to see if I can buy the alternative black strap separate.

 

So out of those options which is more rare/valuable? In kind of a pinch due to only being able to purchase one figure or the game and some other small merchandise.