www.LedBuilder.org has links to some of the high quality and affordable LED grow light companies where you can find afforable pre-built LED grow lights that work really well. DIY kits and information to complete build your own from your own parts are also listed on that website. Some of the best complete LED grow lights are as follows. Put your lemon tree under these and they will produce lemons in the winter. Tasty LED Grow Lights, Johnson Grow Lights, Northern Grow Lights. Chilled Chilled Grow Lights If you want to build your own there are links to lots of resources, and some half-way DIY options you can purchase pre-selected kits of parts like: Growmau5 Grow Kits from Cutter Electronics Timber LED Grow Light Kits If you want to build your own from scratch, you have lots of options on what LEDs and power supplies to buy, you can grow watermelons in your living room if you wanted to. Some of the best parts around are Quantum Boards from Northern Grow Lights. Cree, Vero and Citizen COB LEDS from COBkits Chilled Grow Lights DIY kits These are all high quality options made with mostly the same high-end components that are better than regular shelf-bought grow lights. All this info is available on www.ledbuilder.org

If you assume a 600 lumen output per can, to achieve 35 lumens per sq ft (overall), you need 6 - 7 cans. Besides CFL, LED cans are also available. The Cree LR6 works well and you could consider the cheaper CR6. I used the LR6 as the light was much nicer than cans using CFL. My kitchen is better lit today than before, when I had a 7' ceiling with a recessed light box with t8 lights. Some places (eg - California) require compliance with energy efficiency code (eg - title 24).

We used 4" recessed in all of our 8' ceilings and are happy with it. I would also add that to the degree you get worse diffusion with a 4" light, it really doesn't matter that much as this is a hallway and you aren't spending time there - just passing through.

OP: if you're still undecided, before you do anything or ask your builder to do anything: bring some balloons, painters tape, and string over to the house (and a step ladder.) From the two spots where the current electric boxes are, hang balloons about the same size and distance from the ceiling as lights you might consider, step back, take a picture. Now, same thing but might be a bigger/more blown up balloon (or balloons together), hang from the center of the ceiling as you would a chandelier or other light. Can't find the center of the room easily? Take more string, and tape it crosswise from corner to corner, again corner to corner, to make an X. Where the strings cross is the center of your ceiling. (If my description is confusing see below.) Now hang your balloon 'chandelier', step back, ponder, walk around under it, adjust the string as necessary, take a picture. Here's what I did before hanging a 3 light fixture in my kitchen. I moved my table under it, had a couple of meals there with the kids, and adjusted the strings as necessary. I kept it up for the electrician to see when he hung the new fixture in the spot where the old one was. (the old one is in the background of the picture.) This helped me get exactly what I wanted. :) This method just saved me some time and money for a new fixture in my master bedroom. I had picked out, but not purchased, a new fixture online. I got the dimensions and thought it would be fine as the ceiling in that room is a bit over 10'. I created a mockup based on the dimensions and it was HUGE. I still wasn't convinced so I hung my mockup in the room, and just laughed at the ridiculous look of what I thought I wanted. Found another one that will work much better. :)