Hi @Kristi105
unfortunately there are definitely some guests who will try this on.
In short, you just don't want that sort of guest. Guests who try to bargain you down are notoriously difficult guests who complain, find faults and leave less than glowing reviews. Unfortunately being new, they may see you as a target.
You were absolutely right to stand firm
The only unfortunate thing is that YOU declined the booking, which gets counted against you in your response rate.
Far better to try to get the guests to decline.
either tell them to decline because unfortunately are clearly not going to be comfortable with your listing ( especially if they can do so with out penalty) - and hope they will,
OR you could make things sound so unattractive that they don't want to stay anyway. - talk a lot about your rules and regulation and ask lots of questions or even fib eg "there's a construction site next door and now the toilet has broken and I'm ordering a portaloo for the backyard, I hope you don't mind," or something equally outrageous ( this last can be risky , because those kind of guests might just see it as further ammunition to ask for yet more money off)
Other more experienced hosts will probalby offer more advice.
Take heart though - not every guest is like this and as you gather reviews and get a feel for how to run things, things do get easier.
It's good to read these boards - you learn a lot just skimming through.
Good luck!