Buying a ticket online: best day of week!

Dear all.
I have noticed that on some days Virgin offer different prices for flights, especially the PE (Lowest) category.
Now, as an online marketer (my trade) I understand that offering different individuals different prices in a rotation allows you to find the right price for item (i.e does $995 work better than $1095?). I've done this in the past for many of my clients.
I also have a friend whose husband used to work on the algorithms for pricing airline tickets so I know a little about how they fill up an aeroplane and the pricing (remember this is only a LITTLE so I just comprehend the process!).
What I want to know is:
[?] Do Virgin rotate prices on the site on some days and not others?
Or
[?] Have I just witnessed the computer pricing the seats as it sees fit for that time of demand?
If it's the former then I'd love to know which is the best day or week, even time of day, to buy an airline ticket on the Virgin website. If it's the latter then nevermind and it was worth asking
Lastly, let me tell you the scenario of the booking so you can understand the timeline. I'm flying back to the UK Dec 23rd coming back to the US on Jan 2nd. I'm pricing up, UC (as it's on offer) UC & PE Return and PE the whole way. Each day I look at the prices (sad, I know [:I]) and see if it's going down or up. Once I spot a trend I'll make my decision... doing this you can get great prices!
Any one with any experience of knowledge of the answers here I would be really interested to know what you have to say.
Thanks,
James
I have noticed that on some days Virgin offer different prices for flights, especially the PE (Lowest) category.
Now, as an online marketer (my trade) I understand that offering different individuals different prices in a rotation allows you to find the right price for item (i.e does $995 work better than $1095?). I've done this in the past for many of my clients.
I also have a friend whose husband used to work on the algorithms for pricing airline tickets so I know a little about how they fill up an aeroplane and the pricing (remember this is only a LITTLE so I just comprehend the process!).
What I want to know is:
[?] Do Virgin rotate prices on the site on some days and not others?
Or
[?] Have I just witnessed the computer pricing the seats as it sees fit for that time of demand?
If it's the former then I'd love to know which is the best day or week, even time of day, to buy an airline ticket on the Virgin website. If it's the latter then nevermind and it was worth asking

Lastly, let me tell you the scenario of the booking so you can understand the timeline. I'm flying back to the UK Dec 23rd coming back to the US on Jan 2nd. I'm pricing up, UC (as it's on offer) UC & PE Return and PE the whole way. Each day I look at the prices (sad, I know [:I]) and see if it's going down or up. Once I spot a trend I'll make my decision... doing this you can get great prices!
Any one with any experience of knowledge of the answers here I would be really interested to know what you have to say.
Thanks,
James