Hello Viewers

I am in a bit of a pickle

I have atm a crap little small wattage starter bass amp and am looking to upgrade bass amps
the trouble is that the guitarist is also upgrading to a higher wattage

I was at first looking to get a 100watt Fender Rumble for 660
and my guitarist was gonna get a 65watt custom

although i have read that 3x is wattage is needed.
is this true.??

Now if my guitarists gets a 65 or a 100watt amp
What will i need
and i need reccomendations and low prices ffor best quality.

Thankyou UG

Also i might be able to get a 180watt behringer.
would this do.