Boy oh boy are you lucky!
I moved house in July so I have some TOP TIPS!!
1. Move around the house in unexpected ways. When entering some rooms, jump and twist, this will surprise the owner and make him give you a better deal sometimes. I got £500 off mine because I did a killer Balançoire
2. Slide down the bannister, trust me. I failed to do so in my new house and now I really regret it because the bannister is just too weak to support the bulk of my arse and torso.
3. Lick ALL of the windows for residue. If you taste something that tastes moldy, there MAY BE some mold in the house and trust me this will make you really ill if you keep licking the windows clean.
4. If there is a car on the drive, it probably won't be there if the sale goes through. I thought I had purchased a lovely Volvo, but the bastards took it with them.
5. Count how many roof tiles there are, I counted 783 on my roof and now I check every night to make sure no serious level 4 crimes have happened like some slippery shit nicking off with some to patch their roof up. That, OR WEATHER related incidents - DON'T BE A VICTIM.
6. Kick the radiators. This makes a big, satisfying noise that will make the visit exciting.
7. Ask to look around the house on your own. When you are alone it is much more socially acceptable to sit and read a book in a quiet corner and fart. I farted, but forgot to ask to be on my own and this added on £500 for air purifier expenses.
8. Don't forget it is also your legal right to look in the houses pants and socks draw, if they say no, you know that they are shysters and you must remove their disguises.
9. Test the cooker and other appliances. I took a load of washing to test the washing machine and tumble dryer. I also took some dirty dishes to test their water. I didn't bathe before I went and I tested their shower. I took my car on a rally to test their hose and cleaning equipment (gone when I got there) and I took some pajamas to test the beds. Don't be afraid to ask - everyone does it.
10. During negotiation, use really complex language to confuse your opponent with high level talk moves. Use a pen to accentuate a point you are making and always get in their faces. If possible, come across as mentally unhinged, take a briefcase filled with shit but don't open it or something, this will give you bargaining power. Offer 5% of the value of the house (this might get turned down) and go from there.
I mean really if you follow those TOP TIPS then you should get a good price on the house, take it from me. The house I'm in got valued at £175,000 and I paid at least 6 times that amount which means I beat the banker!
Good luck and don't fall on a spike x