Hello Everyone. I have also decided to undertake the massive task of building a UCS Falcon. I think it was actually Lobot's original post that inspired me to do so.
Anyway, I followed all the tips and went ahead and ordered all the parts from BL, PAB and B&P. And to my surprise it added up to about £830 :/
I'm not sure why it added up to so much, being as Lobot only spent about £650 only 6 months ago. I do realise, however, that I made some mistakes in terms of ordering, BUT I got all the original minifigures and tried to make as few substitutions as possible. Namely:
4589 'Dark Bluish Gray Cone 1 x 1 without Top Groove' (4589b)
4095 'Light Bluish Gray Bar 6.6L with Stop Ring (Patio Umbrella Stand) (63965 - 6L)
3308 'Light Bluish Gray Brick, Arch 1 x 8 x 2' (16577)
50990pb03 'Light Bluish Gray Dish 10 x 10 Inverted (Radar) with Radiating Spokes Pattern on Concave Side' (blank LBG)
75535 'Light Bluish Gray Technic, Pin Connector Round 2L (Pin Joiner Round)' (62462)
4592c05 'Light Bluish Gray Lever Small Base with Light Bluish Gray Lever' (black lever)
3307 'White Brick, Arch 1 x 6 x 2 - Thick Top with Reinforced Underside' (12939)
32555 'Yellow Technic, Brick 5 x 5 Right Angle (1 x 4 - 1 x 4)' (Black)
I have also replaced the dark red 6 x 14 plate with a 6 x 2 and 6 x 12 dark red plates. Oh I also picked black rigging instead of LBG, but I may instead opt for LBG ladder mod, as others have done.
I haven't made as many substitutions as some of you have, but I tried to keep it as original as possible. I even opted for black Technic pins instead of blue. I understand that this could have contributed to the higher total, than I expected (I estimated £650-700 as per my Excel sheet), but it could also be because Christmas is coming, or there's renewed interest in UCS MF due to Episode VII coming out.
In total I made about 20 orders from BL + large orders from PAB and B&P. I'm still waiting for smaller orders to arrive from the continent (they are taking a whil, tbh).
From what I've learned I can offer the following advice in addition to what's already been discussed:
Create a spreadsheet with all the parts listed, as per BL, ideally with pictures, detailed description, part number, colour and quantity required
Look at PAB and B&P to see what's available and write down prices
Do the same for BL and compare prices against PAB and B&P
Order everything (that's not much cheaper at BL) from Lego. Even if it's slighlty more expensive or the same price at Lego as BL, it's still worth getting from Lego.
Trust me, I've left ordering from PAB and B&P til last (about 10 days between initial research and placing orders) and parts 6179, 6565 and 6564 have literally sold out at Lego! They were already expensive at TLG and getting them from BL was even more expensive (that's £10 + postage on top)
Avoid penny pinching!
Look for the rarest items first and see which shops that have them also have the largest number of other pieces needed. Even if a 500+ part order will cost you £5 extra.
The above is something I didn't pay much attention and I ended up making a lot of smaller orders from the continent (Europe) and postage + insurance + other fees added to a lot of money.
Try and order as much from your country as you can - UK in my case. Postage DOES add up to a lot of money. Personally, I didn't order from anywhere outside Europe due to shipping costs + potentially customs fees etc.
Brickficiency probably makes the process much better and is worth using. I didn't use it, because it wasn't giving me the results I was expecting. Basically, suggested shopping lists added up to more than I estimated. This was probably a mistake, as I ended up spending much more in the end.
For me, it was a lot of flipping between BL and Excel, searching for the best price and store stock combination.
I recommend you use BrickStock a lot to create multiple wanted lists and firstly consider what substitions you're willing to make. See what others have done, see what you like and create wanted lists from that. I initially stuck mainly to the original inventory and ended up making last minute additions, which ended up costing me more money.
Oh and one more thing, before you begin, decide what you're going to do about the dish, the engine rigging, etc., and incorporate your choices into your wanted list before you begin the search. I initially went for black rigging and plain dish, but since decided to build one of the mod dishes, as seen in links above, and also use gray ladders for engine rigging. This means more orders to make :)
All in all, I'm happy with the whole thing, despite the total bill (£830) and I'm looking forward to building it. I will post pictures of the process.