@mburkstrand I had not heard of these so I did a little research. That's a nice gift considering the retail on the Sunfires. Are these the Duo / CRM-2? I think they are from around 2007 and they were designed by
Bob Carver who is a well known amplifier designer since the mid 1980s and started Sunfire in 1994. While not a lot of people know about Sunfire speakers, those that do still find them very desirable and you could sell them with proper research and posting to the right places. I think Sunfire is more known for their subwoofers and you can easily find those in the used market. The speakers are rare.
Can't say for certain what they are worth.
A listing on CanuckAudioMart (in Canada) lists a pair of the CRM-2 for C$850 with a retail of C$1600. Over 50% of retail is on the high side in the used market. Someone in Germany is asking $1850 Euro (saying the retail was $2,200 US) but I think they are new. Between 40% - 50% of retail would be reasonable if they are in excellent condition. Eastporters in Canada still have the CRM-2 listed new for C$1100 but that price may be per speaker, so the price is all over the place. In-wall and on-wall Sunfire center speakers are all well over $1100.
Since those are unique speakers, I would be very curious to hear what they sound like. You should hook them up and try them out for a while. You may like them. They are rated down to only 95Hz so they definitely need a subwoofer, so whether you use them in the recroom for TV & music, or just for music in another room, you will want to add a subwoofer. It is common to cross subwoofers at 80Hz but I would recommend a higher crossover frequency for the Sunfires, say 100Hz.
Your budget of $300 is very restrictive as far as audio speakers go. It would be a challenge to find a $300 centre that could match $1600 bookshelves. The big challenge is finding something that has the same sound signature so that dialogue sounds the same when it moves from L to C to R. I looked on
Crutchfield and centers start at around $350 for the Definitive Technology, Wharfedale and Elac centers. If you're on a tight budget,
Monoprice makes inexpensive speakers that are underrated. The Encore C6 is only $250, but something like the THX-365C at $450 would likely pair better with the Sunfires.
If you could get $700 for them and add $300, that's a budget of $1000 for 3 speakers. If you're not looking for "audiophile" speakers, I think it's still doable. There are good bookshelves in the $500-$600 range and you'll want $350 or more for a decent centre that matches.
Audioholics did a nice review of $500 bookshelves which is a good starting point. Soundbars are more for those that do not have the space for a receiver or separate speakers and typically come with a cheap subwoofer that only works with the soundbar. They are compact and unobtrusive, but you sacrifice sound quality and flexibility and are not great for music listening unless you just want some background music. Hope that all helps.