If you're like me and cba to make the crossbow , you could always purchase an Zaryte (60Mish) It's a tier 80 weapon, has no ammo, unlike the Crystal bow and OSRS gold degrades very slowly. The weapons of tier 90 are the Ascension crossbows. They're worth 255Mish . So to purchase both, you'd need to pay 500M or more.
Nex armours are good too however they're certainly not enough for Slayer. I own Pernix and I'm PvP and bossing with it only. I'm using it to camp in the ascension dungeon atm, but that's because I'm trying to get 100 Ranged over the weekend. require as more exp per hour as feasible.
There's an abundance of information in the form of Aza, Fatia and Kamil, I'd just add a few points: A player with maxed stats as you are considering purchasing one of the new POP (Player owned ports, a new D & D) armours. They are available in two typeswhich are a more powerful, non-tradeable variant, or an a little weaker, tradeable version. An important distinction is that the version that can be traded will eventually degrade to dust.
However, these sets of armour require an SIGNIFICANT duration of time to obtain. In the meantime, I'd recommend making use of the Bandos and Armadyl you've saved in the bank. There isn't much to gain from buying Nex sets when you'll end up selling them immediately after you've received POP gear.
Please be aware that all weapons and armor are now organized by level, in order of tier. Dragon needs 60, and therefore is Tier 60; Likewise Barrows is Tier 70. Each weapon of similar tiers have the identical DPSfor example, a rune scimitar is similar to a rune warhammer today. Similarly, all armour sets from the same tier offer the same lifepoint boostas well. Bandos armour provides the same boost to buy RS gold LP that Armadyl which is also the Robes of Subjugation give.