Absolutely it would be but if it were me I'd make an offer of $160. They will counter and if you start too high you won't be able to drop down,
If you are totally new to RVs and RVing it might be worth the cost but you need to expect to pay between $300 & $500 for a good one There are check lists that you can use. A good source of certified inspectors is
the NRIV training group or
NRVTA training school, or just do a search for one.
I have bought both new and used RVs several times and I can't agree with this philosophy. Neither way is perfect and if you get qualified help you can do OK with either new or used. Keep in mind that your choice of a dealer is just as important as the choice of make & model.
I completely agree with the comment about the importance of choosing the right dealer. After researching the dealers here in the northeast for the brand I am looking at, I have decided there is no way I would ever purchase a coach from any of them, and will likely buy something from a dealer on the other side of the country who has a customer service philosophy much more in line with my expectations. The same is true of the reputation of the manufacturer. Those two considerations preempt virtually any other factor for me, way more important than the price that I am able to negotiate.
Regarding your pricing and counter-offer, it's hard to calibrate that without knowing the MSRP. However as one reference point, the opening offer for the coach I am looking at was a little over 20% off MSRP.
As to the decision whether to buy new or pre-owned, I know there are very strong opinions on that, but I have always come down on the side of buying new, buying smart, buying up, and holding it for a long time. Yes, there will be shakedown issues, but see the above dealer/manufacturer point! And you are just as likely to buy someone else's problems with a pre-owned coach, since you have no idea how it was treated, and there is no warranty to cover that. Inspections are a must, but they are not infallible.
While you may not know exactly what you want in the coach on the first time buy, it is easier and cheaper in the long run to adapt it and live with a few minor "gaps", than it is to trade up a couple of times. Transactions costs on that can be 12% or more (sales tax, commission, etc.), and that is a lot of dead-weight loss in the purchase process that can cover a lot of other shortfalls.
Absent any information about MSRP, I would counter between 160-165k.