I did bring this up with my friend who I explained to, that most collectors/DJ's would rather spend £2,000 + on more records than on insurance. After all they've sat there OK for this amount of time. She's determined to keep the prices reasonable with no claims bonuses as well. The insurers will charge less if you have them all catalogued, receipted (E bay buys are easy with Paypal), don't carry them or leave them in the boot of your car etc.
Like I mentioned earlier, you will have the option of just insuring the more expensive records rather than insuring the whole lot. Sounds like she'll have her work cut out. When she does her bit, I'll let you all know.