How much should they cost?
Boots of S&L are $5,500 but also include a +5 bonus to Acrobatics.
$16,000 would be the same as Winged Boots.
Is there a 3rd party version like this?
Thanks in advance
This may be a bit complicated, but it should make sense. If you're confused with any math, I recommend you look at this table to see where I am getting the numbers and formulas for each of these items (and feel free to double check the math in case I mess up; I am human, after all).
Going based off of the reference, Boots of Striding and Springing grant a total of +5 Acrobatics (when jumping only) and +10 Movement Speed and cost a total of 5,500 gold pieces. Now, referencing the Boots of Elvenkind (which also grant a +5 Acrobatics bonus), these boots cost 2,500 gold pieces.
Assuming the wealth value is as listed for purchasing Boots of Striding and Springing, subtracting the total value from the Boots of Elvenkind leaves a total of 3,000 Gold, which we are left to assume is the price cost of the +10 Movement Speed.
Now, there are a few ways we can proceed, but depending on how you want to do it leaves much interpretation. The first method includes the RAW of adding additional effects, which applies a 1.5 times value increase for each other (lesser) value included. However, since these values are the same, it would only apply to one (and not both).
So, we take the +10 Movement Speed cost (3,000 gold), and then double it (in other words, apply another +10 Movement Speed property) to get the desired effect (costing an additional 4,500 gold); these Sprinter's Boots [a name I would coin it] would cost a total of 7,500 gold, as per RAW.
While RAW does cover adding additional effects, it does not cover applying cumulative effects (such as extra uses per day of an ability, or doubling an already-listed effect, etc.), this interpretation may also lead readers to believe that this additional properties rule would not apply to effects that are already listed (and the interpretation is feasible, although personally not recommended), meaning the Sprinter's Boots may instead cost a mere 6,000 gold in the second (more literal) interpretation of RAW.
The RAW also says that sometimes the formulae cited within the book is not pin-point accurate, and recommends that those creating their own items adjust the value as they see fit regarding restrictions of alignment (or class features) as well as its overall viability and power.
Personally, I would say these boots would cost 10,000-15,000 gold pieces approximately, since the movement speed is a huge increase, and is almost as good as the Boots of Speed themselves; however, that's me. YMMV.
I hope this helps!
So I think your math is a little off. 5500 for original boots. 2500 for wonderous item with +5 bonus to a skill. Leaving 3000 gold for the secondary effect of increasing your speed. So we need to convert this to a normal cost by finding 2/3rds of the cost giving us a total cost of 2000 gold for the +10 speed.
The link you posted indicates that most bonuses should be squared and multiplied by a certain number. So if we square 10 feet of movement we come up with 100 which we would have to multiply by 20 to get the 2000 gold. This means that an increase of 20 feet would cost 8000 gold.
OR
Pathfinders uses 5 foot squares as movement. You gain 2 squares of movement for 2000 gold indicating the formula to be bonus squares squared x 500. So 4 squares of movement nets us once agian 8000 gold.
The one thing that is suspect in this math is assuming that 2500 actually goes to increasing a skill as the skill bonus is limited to a bonus to jumping only. A rough estimate would decrease this value by 2/3rds. If this value is reduced by half then it becomes the secondary effect and the cost of the movement goes up. So assuming that the cost is reduced for an initial cost of 833 gold x1.5 for a secondary effect the cost of the jump bonus is now 1250 which brings up messy math. So assume a cost of 1500 gold for jump bonus. Leaving a cost of 4000 gold for speed increase.
Using the formula bonus movement squares squared x 1000
5 extra feet of movement 1000 gold
10 extra feet of movement 4k gold
15 extra feet of movement 9k gold
20 extra feet of movement 16k gold
I find this last formula to be most in line with curent game standards.