Vet costs for a guinea pig?

[MsMarvel]

Guinea pig is poorly and is on her way to the vets just now with dp. Its very possibly just old age, was a rescue pig when we got her, and we've had her for around 4 years now.

Is this going to be an expensive vets visit...? Will they be honest if she's just old and put her to sleep? Don't want her to be in pain but don't want to draw out an inevitable outcome iykwim

not sure whether to start my own thread but i have a vets bill guinea pig dilemma

our gp is nearly 4

i took her to have her nails clipped at the vets on saturday (she goes crazy whenever we have tried and they were getting desperate). The vet immediately asked how long the lump on her hip had been there? We hadn't noticed. It is quite a big lump but right on her hip, it is obvious now that it's been pointed out. The vet did a biopsy to see what it was and has just phoned with the results. It is benign but she said it needs to be removed before it gets much bigger - when it will be difficult to remove.

I paid £79 for the nail clipping and biopsy on saturday
The cost for the lump removal will be £260

i know dh will tell me to do it. the kids will tell me to do it. i am not sure i can part with this amount of money!

any advice or suggestions re how necessary it is to remove it? TIA