I would ask yourself these questions before boosting:

1. What tier is your current pet and what tier are the best weapons in your armory?
2. If you boosted, would you reach the desired tier you want to be in?

It doesn't make sense to boost to T10+ if you don't have T10+ weapons or the funds to buy T10+ weapons. I have seen some people with T12 pets that struggle with battling because they don't have the armory to support their pet or the strategy you gain from battling experience because all they have ever done was trained and boosted with very little battling in between.

Maybe save a bit up before you use them, Although Ive spent billions, I do have a vast wardrobe/armory/whatever to fall back on so its not such a problem for me. However, if you have your armory built for your new tier you'll be and dont mind saving up again, go for it!

Make sure your armory is suitable for your new tier though, I must stress that! I always bought my new set before boosting :)

What weapons do you have in your armory now? What is your budget? How far away are you from T10?

Mirroring Shield of Brilliance

Phoenix Quill

Rainbow Vortex

Risen

Shinwas Temple Shard

SubetaBall

Infinite

Ok so looking at your armory I would hold off on boosting and focusing on upgrading your set. Depending on how many tomes you have, you may be able to reach T10 just through training and then jump right into T11. I would focus on a T10/T11 battle set.

An ideal armory has a high dark blocking weapon, high light blocking weapon, high earth blocking weapon, high water blocking weapon, etc to switch between depending on your opponent. There are some nice entry level weapons though if you are low on funds. is a decent dark blocker once you hit 2,500 defense. is a decent water blocker and gets better as you increase speed. is a very good earth blocker, but will be expensive. are interesting to use. The icons they block changes as you go up in tiers. At T10 strength they block magma but that will change as your strength increases. is a nice T10 weapon to block ice and magma but is expensive. I would definitely make in the battle shop with the tokens you win from battle quests. This is T9 so you can use it now. It is 100% freeze OPB item that protects your from freezing for 2 turns.

wesker should I pay 50m for that helmet? also what is a good price to pay for each tome?

: You can save up tokens to buy the helmet from the battle shop and save 50 mil for other battle stuff. The helmet is extremely helpful for General Error, but apart from him you can do just fine with other freezer.

Also visit the Set advice subforum. Your original post asking about tier 9 weapons seem to have been moved there :)

: Here you are ^^

As Maskros said, don't buy the helmet from shops, you can make it in the battle shop with extremely hard tokens. The helmet is very useful. My pet is T12 and it's still a staple in my set.

As for the tomes, I was able to buy them at 2.5 mil per tome. Some friends or people I bought regularly from in bulk would sell them to me at 2mil per tome though.

lucky.. :( I spent 3.1 on each lol

Buying amulets at 315K per amulet on average gives you tomes at 1.8mil each...

I've used 1600 amulets in the last 3 days trust me thats the odds in large numbers

is right. If you buy huge quantities of them, it pays off in the end. I just don't have the patience to turn in all those amulets and watch the mage give me a bunch of shards.