Really depends on whether you want it to be passively marketed or actively pitched to investors and buyers, as well as how fast you want it sold. It also depends on what you're selling. What you're selling is only worth ANYTHING if there is an interested buyer. And it's only worth what the buyer is willing to pay for it at the time you want to sell it, not what you currently owe on your RV. This is a common misperception among folks trying to value domains before sale - they pick some nebulous method of pricing it that is not based on the market or history or sector demand, but rather on what a vacation costs or how much they owe on their boat. Good luck with that. So it really depends. If you have something that you feel has demand, you'll potentially get a higher price for it by NOT needing to short sell it quickly for cash and being able to wait while a broker packages and pitches it. 60-90 days. That will always get a higher price than just listing it in a database and hoping someone will see it and be interested. The problem is, good brokers are few and you're going to need to see if they will represent you in the sale. If they don't believe they can sell it at all, or they don't believe they can sell it for what you owe on your boat, they'll decline your offer to do business with you because you're being unrealistic.
That said, my recommended budget for beginners would be $500+. Using this budget you could buy a bunch of high-potential $10 domain names, expired/dropped domain names or a mix of both. It’s very important to invest only what you can afford to lose and treat this as a side hustle till you get the momentum going. As you gain experience, industry expertise and some sales under your belt, you can then consider slowly growing your business into a full-time gig.