Hi ndfnd,
I have a 4 year old female tabby that i have adopted for abt 2.5 years and now, I added a new family member which is a 5 month old female domestic LH which I have bought about 2 months ago.
My tabby, Momo, came from a multicat household but have been on her own ever since she was adopted by me. My household is very private and calm (no kids and human traffic) so she had me all to herself. However, I was getting a little worried that she is overdependent on me as she gets rather distressed when i am not at home with her. Even on short weekend trips, when i arrange for a good pal to house-sit for me, she has a slight tendency to show her depression by peeing on the upholstery. You had no idea how many times I had to either wash or totally replace my furniture!!
So, after careful consideration with my partner, who incidentally is the one who suggested we get another kitty to accompany Momo, I 'accidentally' chanced upon our new kitten, Bridget at a pet store in bangsar.
I had been out getting my daily groceries when i popped into the pet store to say hi to the friendly pet store owner. What luck...bridget was in the grooming room with 2 of her siblings ready for purchase next week.
well, the rest is history.
anyway, cost wise has not been significantly different then having one cat. the amount of litter used has increased slightly as i now use 2 litter trays instead of one. one medium and one small tray. They are very polite and hygienic when it comes to toilet manners and none of them have a tendency to 'mark' their territory, being female cats and all.
after the initial set of compulsory vaccination required for a kitten in the first 12 weeks of its life, there are no more visits to the vet unless it is sick, until the end of the year for booster shots.
my two cats don't over eat so there has been no influx in the cost of food as well.
I would say that it is almost the same amount of care and cash needed to have 2 cats compared to having one. Except, it is a good idea to always ensure there is sufficent water and food for both and that the litter tray is kept immaculately clean.