We support the two top tiers of storage vendors arrays. These would both be classified as enterprise class storage devices. Eg Tier 1 arrays - DMX, USP-V, VSP, XP etc and Tier 2 being AMS, EVA, DS etc. All our supported arrays are listed in the V-Series support matrix. It would depend on commercials as too which would be the cheapest but I wouldn't suggest any would fit into the category of 'cheap' storage.
As Paul responded, the intent and policy is to support widely-used mid-range and high-end storage arrays. NetApp does not support entry or 'cheap' storage arrays for various technical, logistical and business reasons.