We have an 8 month old cavalier x toy poodle. We met her dam (cavalier), dam's mum (a health older cavalier) and the sire.
In terms of costs, she's fed on Eden which is around £60 for around 4 months worth of food. I recommend looking at the all about dog food website. Then we pay more for treats, chicken etc...
We pay £20 for grooming every 6-8 weeks. We brush her every day; so factor in cost of brushes, any spray shampoos, wipes etc...
We also pay £20 a month to be part of the local vet health plan, but we are also looking at taking out an additional insurance policy. The insurance policy will cover third party insurance and things like holiday curtailment.
The health issues are a big risk, and we discussed the risks with our vet before we got her.
We pay £30 for dog training classes; 6 week course, 1 hour a week. This will include the Kennel Club good citizen award. She has been a pleasure to train, but we put a do lot of effort into it. She's very active.
Dog boarding costs too; we were determined to find the best one locally because we are likely to need some hospital care next year so wanted to make sure our dog is happy.
I am by no means am expert so I can only answer from a new owner's perspective.