Why do we have so many different lamp types in our e-shop?

In our e-shop you can find up to seven lamp options for your projector or television. Original lamps with housing, supplied directly from projector manufacturers, are often relatively expensive and are not always available. For these reasons, other types of lamps have started to appear on the market. Please see a brief description of them here:

Original lamps with housing – supplied directly from projector manufacturers; this is the most reliable but also the most expensive option.
Dual original lamps with housinge – a pack of two original lamps with housing for two-lamp projectors.
Original bulb inside – equipped with bulbs from one of the manufacturers of original projector bulbs; however, the lamp housing is produced by generic manufacturers.
Diamond lamps – quality lamp housing produced by the Diamond Lamps Company; equipped with original bulbs, most commonly Philips and Osram brands.
Generic lamps with housing – assembled with components from different manufacturers; they are often of lower quality, yet are still usually much cheaper than original lamps with housing.
Original lamps without housing – these are bare bulbs from one of the manufacturers of original projector bulbs.
Generic lamps without housing – bare bulbs produced by generic manufacturers, although they often do not have the same quality as original bulbs.