I'm sorry you haven't found your new piggies as much of a joy as your would've hoped. Don't loose heart. Piggies can be noisy but as mentioned above noise is usually from them enjoying themselves. There's plenty of cheap ways you can make toys for them, like cardboard boxes with entrances and exits cut out, toilet roll tubes (with a slit down one side so they can't get stuck) paper bags.
In terms of expense, I, and many others on here, find that purchasing from local farm shops, or online retailers, often works out much cheaper than places like pets at home for example. Hay will be the largest ongoing cost, but it is essential, and if you look around at options, you can get it rather cheap. I've found my pigs are more wasteful when it comes to using a hay rack, as they pull the hay out and don't eat it. But I now use a hay box, it's actually a cheap cat litter tray, and I line this with wood shavings, to then put a handful of hay in at a time. Unfortunately it's inevitable that some hay will be wasted, but in the grand scheme of a bag of hay, I find little is wasted this way, but it may be different for your pigs, it's a case trial and error.
Can I remind you that small amounts should be put by for veterinary costs every so often, this will later reduce stress if one of your piggies falls unwell.
In terms of smell, piggies generally are very clean, I have 4 in my bedroom, and don't find them smelly at all (until the day before cage clean)
What type of bedding you use and how often you clean it will affect how much your pigs smell.
The most common types of bedding are wood shavings, paper based bedding and fleece. I personally use fleece, as once you've got the fleece and towels, it's much less wasteful, bur your parents may not appreciate having to wash the pigs bedding in the washing machine, this would be something you'd have to ask them about.
Bedding like wood shavings, should be spot cleaned daily, and wet patches should be removed and replaced with clean bedding, doing this daily will to help minimise smell.
I find the hay box also helps with smell control, and the pigs use this as a toilet too so I simply empty this out more regularly than I change their whole bed.
I hope this is of some help to you, any more questions feel free to ask
