You'd be hardpressed to find parts for that DP if it turns out to be from way back the 1990s. If you buy it and it breaks down a year or so from now, you'd probably still be lucky if you'd find someone who'd repair it or have spare parts for it.
If budget is a problem, I suggest just going for brand new DPs (those that cost sub-$700). You can always wait and save up a couple of more months for a brand new DP for less than $700 bucks (try searching on-line) which will save you from headaches as to warranty claims and parts repair (if ever it breaks down a couple of years from now).
If you're really a ROLAND product follower, you can try searching for either:
1) discounted "slightly" blemished items
2) used but FAIRLY recent models
If you're open to DPs made by other companies that cost less than $800:
1) You can try the Casio Privia w/ 128-note polyphony (PX 120/PX-200/PX-320)- costs either less than $600 (for PX-200, PX-120) or less than $700 (PX-320)
2) You can try the Yamaha DGX 620 (32-note polyphony only) or the P-85 (64-note polyphony)
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Creativity lies not only in your ability to make original music compositions but also in your ability to create your own unique interpretation/arrangement of another person's music (with the necessary permission/acknowledgment of the composer, of course)