Just getting started on a budget and need bookshelf speakers/receiver now

This might work for you and is within your budget. Music Direct has the well regarded Wharfedale - Diamond 10.2 speakers on sale for $299. You can get a Yamaha A-S501 Integrated on Ebay for $349. I've never heard either, just an option from good companies.

https://www.musicdirect.com/speakers/wharfedale-diamond-102-bookshelf-speakers-pr-awfdia102blk
https://www.ebay.com/itm/YAMAHA-A-S501-170-watt-Stereo-Integrated-Amp-DAC-with-sub-out-AUTHORIZED-DE...

So you can go to a dealer, and buy new, and it will sound great because you’ll be able to hear it all first, and make sure it sounds great. Or you can buy used, and save a ton of money, but then you have to resell stuff that doesn’t work. Problem is, unless you buy local, the shipping costs are going to take most of your cash, so used isn’t much help. If you are buying local, though, then many sellers are more than happy to share their thoughts and knowledge, and that includes letting you come and listen, before you buy. That’s true of dealers too: many hifi dealers do it because they love music. I’ve gotten used kit from dealers that had upgraded their big spending clients. (I am a very little fish). Don’t rush. Unless they’ve been abused, speakers don’t really get worse with age. I have a set of 20 year old meridians and they are the most amazing thing I’ve ever heard. So that's $25,000 of speakers (in 1995 dollars) for ~$1400. I can't give you specific recommendations for Opera. But for me, buying used has been very rewarding.

I went old school/new school on my budget. Old school Marantz Model 18, and a Technics SL-1200MK2. New school, Elac Uni-Fi UB5 speakers. I purchased all three for a total of $1500. It’s a great combination, and I couldn’t be happier. 

I can only speak in reference to NAD gear mentioned by other posters. If you pursue that route look at sites that have the NAD 3020 integrated amp for sale. That amp has been out of production for quite some time but in the used market you may be able to find one that is in excellent condition or has been refurbished. The 3020 was a big dog killer in it's day because of it's performance compared to amps costing much more.
If you do decide on a NAD pay close attention to the speakers to be used with it. Some sound not good like Klipsch and others. NAD and PSB were or are kinda like sister companies. PSB mates well with NAD stuff. PSB offers many lines in terms of price.

Don’t forget the vintage NAD 7020, which is the 3020 with a receiver. Just got one off of eBay and had my guy replace some caps and clean it up. Total invested $200. Replaced my 15 year old Paradigm Atoms with new ELAC Debut 6.2s that we’re on sale on Amazon for $150. Great sound for $350 all in.