I bought do it your self NIW package (including rfe) last year for $140, now ask for $40 for sale.
I also have EB1 and EB2 recommendation letters samples (9 letters) for biological or medical research areas for sale, asking for $60.
Cover letter, asking for $50.
I used these sample letters and do DIY package and sucessfully applied EB1 and EB2 at the same time.
If you don't want to spend thousands dollars to hire a lawyer, those materials above should be good enough for you.
If you are interested, you can email me at ldy_wang@yahoo.com