CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net income	$ 116,413	$ 48,508	$ 37,263
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	5,411	3,249	2,682
Equity-based compensation	5,741	2,213	154
(Gain) loss on asset disposals	(94)	10	1,371
Change in fair value of warrant liability	0	(771)	(1,336)
Loss on extinguishment of debt	0	6,559	0
Non-cash interest expense	659	477	3,478
Deferred income tax provision	3,728	509	0
Loss (gain) on contingent consideration	2,872	5,520	(1,674)
(Increase) decrease in assets:
Accounts receivable	(9,531)	(3,185)	(2,344)
Inventories	25,289	127,214	(38,954)
Prepaid expenses and other current assets	(18,924)	(7,984)	(5,565)
Deposits	(173)	(5)	2
Increase (decrease) in liabilities:
Accounts payable	(26)	7,235	(966)
Other payables and accrued expenses	4,010	10,528	614
Customer deposits	24,048	12,400	(450)
Net cash provided by operating activities	159,423	212,477	(5,725)
Cash flows from investing activities
Purchases of property and equipment and construction in progress	(9,896)	(6,309)	(7,291)
Proceeds from disposal of property and equipment	233	1,637	73
Proceeds from sale and leaseback	0	0	15,623
Cash used in acquisitions	(107,467)	0	(19,403)
Net cash used in investing activities	(117,130)	(4,672)	(10,998)
Cash flows from financing activities
Net (payments) borrowings from floor plan	(23,497)	(101,342)	24,401
Proceeds from long-term debt	30,000	129,306	13,801
Payments on long-term debt	(8,878)	(121,800)	(9,942)
Payments of debt issuance costs	(701)	(3,910)	(203)
Payments of debt extinguishment costs	0	(4,207)	0
Payments of initial public offering costs	0	(5,646)	(1,148)
Payments of September offering costs	(540)	0	0
Payment of acquisition contingent consideration	0	(1,456)	0
Distributions to redeemable preferred interest members	0	(90,503)	(3,364)
Proceeds from issuance of Class A common stock sold in initial public offering, net of underwriting discounts and commissions	0	59,234	0
Proceeds from issuance of Class A common stock sold in September offering, net of underwriting discounts and commissions	0	8,075	0
Payments of tax withholdings for equity-based awards	(802)	0	0
Dividends and distributions	(27,070)	0	0
Distributions to members	(5,009)	(18,895)	(11,087)
Net cash used in financing activities	(36,497)	(151,144)	12,458
Net change in cash	5,796	56,661	(4,265)
Cash and restricted cash at beginning of period	68,153	11,492	15,757
Cash and restricted cash at end of period	73,949	68,153	11,492
Supplemental cash flow disclosures
Cash paid for interest	6,251	17,212	12,485
Cash paid for income taxes	28,537	246	0
Noncash items
Acquisition purchase price funded by long-term debt	0	0	18,800
Acquisition purchase price funded by seller notes payable	2,056	0	10,438
Acquisition purchase price funded by contingent consideration	9,200	0	0
Acquisition purchase price funded by issuance of Class A common stock	1,495	0	0
Accrued purchase consideration	1,889	0	0
Purchase of property and equipment funded by long-term debt	1,820	1,190	1,067
Dividends payable	1,035	0	0
Distributions payable	4,964	0	0
Offering costs, accrued not yet paid	0	430	1,500
Initial operating lease right-of-use-assets for adoption of Topic 842	$ 71,823	$ 0	$ 0