Development kit lenses

Those 5x lenses you are using have a much longer focal length than the Rift lenses
The problem with these lower magnification optics
The optics in the Rift are at the limits of what you can do with conventional acrylic lens technology
Making larger lenses with similar magnification is not practical at this point in time

A New Approach to Characterising Aspheric Surfaces : http://eprints.soton.ac.uk/51013/

7.2" screen

Condenseur 51mm Pyrex http://www.fresnels.fr/achat/produit_details.php?id=19&PHPSESSID=a7e9759040a3c8734143cba782944cdd

5.7" 16:9 screen

A. JAEGERS PYREX PCX ASPHERIC LENS 44.1MM DIA, 30MM FL ($8.00) : http://www.surplusshed.com/pages/item/l3786.html

5.6" 16:10 screen


Aspheric lenses


5X magnification

5x pocket loupe magnifier with Aspheric Lens
http://www.ebay.com/itm/5x-pocket-loupe-magnifier-with-Aspheric-Lens-/251148139033?pt=LH_DefaultDomain_0&hash=item3a79987a19
http://www.magnifier.com/aspheric_magnifiers.htm
2" / 5.1 cm focal distance
50.00 mm lens diameter

Bausch & Lomb Aspeheric Packette, 5x ($10.16) : http://www.amazon.com/gp/product/B000M755GK/
Round Magnifier with Cover, 5x, 2" ($5.91) : http://www.officesupplyinc.com/round-magnifier-with-cover-black-frame-p-3227.html
Bausch & Lomb 5x Aspheric Lens Pocket-Size Magnifier ($9.50) : http://www.jakesmp.com/csd_magnifiers/CSD_Magnifiers_024_NF_BauschLomb_mags_C.html

High magnification

Aspheric Magnifier 10x - 36D 35mm ($15.95) : http://www.amazon.com/Aspheric-Magnifier-10x-36D-35mm/dp/B00012KCWS

Aspheric Magnifier 12x 44D 35mm ($15.95) : http://www.amazon.com/Aspheric-Magnifier-12x-44D-35mm/dp/B00012KCXW/

12X LED Switch Light Hand Held Reading Map Magnifier ($3.56) : http://www.amazon.com/Switch-Light-Hand-Reading-Magnifier/dp/B005E43I7O

Spherical lenses ?


Magnifier and Tweezers with LED (6x 2" $4.97 in store) : http://www.walmart.com/ip/Magnifier-and-Tweezers-with-LED/19757912

School Smart All-Purpose Magnifier, 6x Magnification, 2" Lens Diameter (6x 2" $0.99) : http://www.amazon.com/School-Smart-All-Purpose-Magnifier-Magnification/dp/B0044S5H84/

38mm Diameter Double Convex Lens Focal Length 50mm Educational Lens Optics & Light (£2.95) : http://www.amazon.co.uk/Diameter-Double-Convex-Length-Educational/dp/B00IST5L2M

Double Convex 3.75 cm Diameter, 5 cm Focal Length ($1.35) optical glass : http://www.enasco.com/product/SB10476M
http://www.reddit.com/r/oculus/comments/22xmey/this_only_makes_me_want_a_rift_more_diy_cellphone/

LEEP like lenses

DCX Lens - 62.8mm dia. x 72.4mm FL http://www.anchoroptics.com/catalog/product.cfm?id=268&iid=20087 PCX Lens - 43mm dia. x 77mm FL http://www.anchoroptics.com/catalog/product.cfm?id=253&iid=21253

Fresnel lenses


Phones and tablets

UltraOptix SV-2LPLED 7X Aspheric LED Lighted Magnifier http://www.amazon.com/UltraOptix-Powerful-ASPHERIC-Lighted-Magnifier/dp/B0054H1XYQ
http://ultraoptix.com/collections/magnifiers/products/sv-2lpled

LENSES FOR GOOGLE'S NEW DIY CARDBOARD VIRTUAL REALITY SMARTPHONE VIEWER : http://www.surplusshed.com/pages/item/l8672.html
  • L10947: BCX 23mm diameter by 39mm focal length
  • L10946: BCX 35mm diameter by 40mm focal length
  • L13848: DCX 25.4mm diameter by 43mm focal length
  • B1096: DCX 26mm diameter by 45mm focal length

Tablets

UltraOptix SV-3LPLED 4X Aspheric LED Lighted Magnifier http://www.amazon.com/UltraOptix-Round-Magnifier-Power-SV-3LPLEDSV-3LPLED/dp/B0019NA0S4

FOV2GO
VR2GO
Socket HMD
MxR Lens mod

https://www.reddit.com/r/oculus/comments/75atjx/valve_develops_custom_vr_lenses_for_next/do5b7vw/