Here's my grading scale, adopted from the Toy scale. You can at least grade it. I can tell you that the Quadra 700 is a fairly popular model. You can check the Completed Auctions on eBay to get an idea of what they sell for on eBay.
Terminology:
Mint+ = Same as mint, but may include additional period accessories, documentation, or carry technical/historical significance.
Mint = Never opened. Box shows regular shelf wear.
Near Mint = Never opened. Box suffered from major defects.
Mint in Box = Same as Mint, but box has been opened. Contents have otherwise remained untouched.
Near Mint in Box = Same as Near Mint, but box has been opened. Contents have otherwise remained untouched.
Boxed = Complete and includes the box in varying condition.
Complete = Includes everything except the box, such as accessories, software, manuals, and documentation in varying condition.
Incomplete = Missing one or more items above.
Condition:
New = Computer has never been used.
Like New = Computer looks an functions as new.
Excellent = Computer had little use, has no discoloration, scratches, chips, or cracks.
Very Good = Computer had some use, has minor discoloration, but no scratches, chips, or cracks.
Good = Computer is used and may have minor to medium discoloration and/or some scratches, but no cracks.
Used = Computer is well used and may have medium to major discoloration, scratches, and/or chips, but no cracks.
Poor = Computer is in poor condition, may have major discoloration, scratches, chips, and/or cracks.
Other Terminology that may affect value:
No Boot = Turns on, but doesn't boot.
Nonworking = Doesn't turn on.
For Parts = Machine is only useable for spare parts.
Development = Computer intended for developers outside the company.
Prototype = Pre-production computer for internal development only.
Limited = Limited edition or only produced in very small quantities.
Corrosion = Battery and/or capacitor leak, components may be irreparably damaged.
Recap = Capacitors have been replaced.
VCS [Vintage Computing Scale]:
50+ - Mint+.
50 - Mint. ***
48 - Near Mint. ***
46 - Mint in Box.
44 - Near Mint in Box.
42 - Computer is New and Complete.
40 - Computer is New and Incomplete.
38 - Computer is Like New and Boxed.
36 - Computer is Excellent and Boxed.
34 - Computer is Like New and Complete.
32 - Computer is Excellent and Complete.
30 - Computer is Like New and Incomplete.
28 - Computer is Very Good and Boxed.
26 - Computer is Excellent and Incomplete.
24 - Computer is Very Good and Complete.
22 - Computer is Good and Boxed.
20 - Computer is Good and Complete.
18 - Computer is Used and Boxed.
16 - Computer is Good and Incomplete.
14 - Computer is Used and Complete.
12 - Computer is Used and Incomplete.
10 - Computer is Poor and Boxed.
8 - Computer is Poor and Complete.
6 - Computer is Poor and Incomplete.
4 - Working, For Parts.
2 - Non-working, For Parts.
*** Mint or Near Mint versus Mint In Box or Near Mint In Box: There is a lot of fun to be had in opening a vintage computer for the very first time. However, there is a very important factor to include when determining the best price before purchasing. Because most computers shipped with a battery installed, due to their age and depending on the quality of the battery, it is possible that the battery has leaked and corroded the internal components. Additionally, electrolytic and paper capacitors have a tendency to bulge and leak over time, leading to possible corrosion. Without first opening a box and inspecting a computer, it is unknown if a battery or capacitors have done so. Due to the ever increasing age of vintage computers, it is becoming more and more likely for this to occur. Therefore, while Mint and Near Mint are at the top of the scale, the value of the computer may not always coincide with the grade due to these unforeseeable factors. Be careful with unopened vintage equipment, and if possible, ask the seller to inspect the computer first.
