Hello all. Thank you for taking a moment to read this & offer your suggestions/ advice. I'm sure my basic question has been asked many times: "In your opinion or experience, what are the first, most important, necessary accessories I should add in order to maximize the the use and ease of a newly acquired Celestron Nexstar 127 SLT ? I have a power supply adapter, 9mm,10mm, 25mm eyepieces, 2x Barlow and 90 degree diagonal mirror adaptor. With a modest budget and a 2 week deadline, I've researched numerous reviews and narrowed some choices to additional Plossl eyepieces, an assortment of filters or a dew shield. All of and these can probably be purchased within my budget but I'm even willing to take the plunge on an upgrade to a better mount, which I have no idea where to start. Any and all suggestions, advice and opinions are gladly appreciated. Thank you all, from across the pond in northeastern US.